6.2.4: Role of the Home Health Aide/Personal Care Aide
The role of a Home Health Aide/Personal Care Aide will vary depending on the needs of the patient with a developmental disability and their family. For many patients, Home Health Aides/Personal Care Aides will assist with providing or assisting to provide self-care. The personal care skills covered in previous modules and in future modules in this course will all be used to work with a patient with a developmental disability. This includes bathing, skin care, and dressing, toileting, feeding, and assisting with ambulation.
Home Health Aides/Personal Care Aides will monitor their patient’s health as directed by the Care Plan. They may be asked to measure intake and output. They may assist with housekeeping and meal preparation for their patient. They may provide respite for the family and assist with supervision and child care while the family is busy with another task or to allow them some respite.
As with all patients, using good communication skills is important and essential in doing their job well and meeting the needs of their patient. It will also be part of the job to help teach patients who need help learning effective communication skills. As with all patients, an important part of the job is to always be observing and documenting changes in physical, mental, emotional, or social health.
Report any issues of concern to a supervisor immediately. Always be sure to document any observations and tasks that you have completed and only once they are completed. Be watchful of issues of concern in the home such as domestic violence, substance abuse, or child abuse. Report any concerns to a supervisor immediately.
Performance Standards
Home Health Aides/Personal Care Aides will use all of the basic skills they have learned in working with people with developmental disabilities. Remember the following:
- Speak to all people respectfully and politely.
- Include the patient in conversations. Speak with and not about them. Do not assume they cannot understand what is being said about them.
- Use positive verbal and nonverbal communication skills. Avoid negative communication.
- Explain things in a way the patient will understand. Observe how they receive information and make adjustments to how you communicate based on their understanding.
- Encourage the patient to think by asking questions rather than just giving commands to them. Allow them a chance to respond and to make choices.
- Encourage independence by allowing the patient to do as much as they can rather than doing for them. Be patient and allow extra time for task completing. Give praise and encouragement. Never be negative or criticize the patient when they try to complete a task.
- Include the patient in decisions and provide choices to them whenever possible. This promotes self-determination and independence.
- Always respect differences and individual desires, needs, and values.
- Consider others’ feelings and concerns, even if they are different from your own. We are all different, and will have differences in opinion and values. Never be judgmental.
 While Home Health Aides/Personal Care Aides may need to make adjustments in how they complete tasks or how they communicate, the basic set of skills and performance standards are required for work with every patient. Following these will allow Home Health Aides/Personal Care Aides to provide the best care they can and to allow their patient to become as independent as possible.


1.3.8: Calorimetry- Titration Microcalorimetry- Micelle Deaggregation
Aliquots of a concentrated surfactant solution are injected into the sample cell of a titration microcalorimeter. The sample cell initially contains water(\(\lambda\)). As more surfactant solution is injected into the sample cell a stage is reached where the concentration of surfactant in the sample cells exceeds the critical micellar concentration, \(\mathrm{cmc}\). The magnitude of the recorded heat changes dramatically, leading to estimates of both the cmc and the enthalpy of micelle formation.
This calorimetric techniques has proved important in studies of ionic surfactants; e.g. hexadecyltrimethylammonium bromide (CTAB). For these surfactants the microcalorimeter signals a marked difference in recorded heats as the concentration of the surfactant changes from below to above the cmc. Titration microcalorimetric results for non-ionic surfactants are unfortunately not so readily interpreted. In addition to micelle formation, the monomers cluster in small aggregates below the cmc and the micelles cluster above the cmc.
Analysis
The volume of injected aliquot \(\operatorname{vinj}\) is significantly less than the volume of the sample cell. The amount of surfactant in each aliquot is \(\operatorname{ninj}\), the concentration of surfactant being \(\operatorname{cinj}[=\operatorname{ninj} / \text { vinj }]\). If \(\operatorname{cinj}\) is significantly above the \(\mathrm{cmc}\), the contribution of the surfactant to the enthalpy of the injected aliquot is \(\operatorname{ninj} \, \mathrm{H}_{\mathrm{j}}^{0}(\mathrm{mic})\) where \(\mathrm{H}_{\mathrm{j}}^{0}(\mathrm{mic})\) is the contribution of one mole of monomer to the molar enthalpy of a micelle. If the concentration of solution in the sample cell is below the cmc, the contribution of each monomer to the enthalpy of the solution equals \(\mathrm{H}_{\mathrm{j}}^{0}(\text { mon })\). We concentrate attention on the contribution of the surfactant to the enthalpies of injected solution and the solution in the sample cell.
Enthalpy of the injected aliquot, \[\mathrm{H}(\mathrm{inj})=\operatorname{ninj} \, \mathrm{H}_{\mathrm{j}}^{0}(\mathrm{mic}) \nonumber \]
The contribution of the surfactant to the enthalpy of the solution in the sample cell at injection number I is given by equation (b).
Enthalpy of solution in the sample cell at injection number I, \[\mathrm{H}(\mathrm{I})=\mathrm{I} \, \operatorname{ninj} \, \mathrm{H}_{\mathrm{j}}^{0} \text { (mon) } \nonumber \]
Enthalpy of solution in the sample cell at injection number (I+1), \[\mathrm{H}(\mathrm{I}+1)=(\mathrm{I}+1) \, \operatorname{ninj} \, \mathrm{H}_{\mathrm{j}}^{0} \text { (mon) } \nonumber \]
Recorded heat \[\mathrm{q}=\mathrm{H}(!+1)-\mathrm{H}(\mathrm{I})-\mathrm{H}(\text { inj }) \nonumber \]
\[\text { or, }[\mathrm{q} / \text { ninj }]_{\text {lowl }}=\mathrm{H}_{\mathrm{j}}^{0}(\mathrm{mon})-\mathrm{H}_{\mathrm{j}}^{0}(\mathrm{mic})=-\Delta_{\text {mic }} \mathrm{H}^{0} \nonumber \]
At high injection numbers the enthalpies of solution in the sample cell are \(\mathrm{I} \, \operatorname{ninj} \, \mathrm{H}_{\mathrm{j}}^{0}(\mathrm{mic})\) and \((\mathrm{I}+1) \, \operatorname{ninj} \, \mathrm{H}_{\mathrm{j}}^{0}(\mathrm{mic})\). \[[\mathrm{q} / \text { ninj }]_{\text {highl }}=(\mathrm{I}+1) \, \mathrm{H}_{\mathrm{j}}^{0}(\mathrm{mic})-\mathrm{I} \, \mathrm{H}_{\mathrm{j}}^{0}(\text { mic })-\mathrm{H}_{\mathrm{j}}^{0}(\text { mic })=0 \nonumber \]
At low injection numbers the recorded \((q/\operatorname{ninj}\)) is effectively the enthalpy of micelle formation. The recorded ratio \([q/\operatorname{ninj}]\) is effectively zero at high injection numbers, the switch in pattern of \((q/\operatorname{ninj}\)) from \(\Delta_{\operatorname{mic}} \mathrm{H}^{0}\) to zero marking the cmc of the surfactant.


4.2: The Cultural Landscape
Cultures’ beings rely on natural resources to survive. In the case of rural cultures, those resources tend to be local. For urban cultures, those resources can either be local, or they can be products brought from great distances. Either way,cultures influence landscapes and in turn landscapes influence cultures.
The physical landscape consists of places like the Appalachian Mountains that stretch across a large portion of North America, the Mongolian-Manchurian grasslands, the Amazon river basin, or any other environment. These are landscapes that have been formed over thousands, if not millions of years by forces of nature. In order to live in places a different as these, humans have needed to adapt their lifestyles. The relationship between people, their culture, and the physical landscape is known as human-environment interaction. This relationship is reciprocal; culture adapts to a particular place, and that place is changed by people. Cultural ecology refers to the types of landscapes created by the interaction of people and their physical environment.
Humans have been thinking about the relationship between people and their environments for a considerable amount of recorded history. In the book On Airs, Waters, and Places , the Greek philosopher Hippocrates wrote that different climates produced different kinds of people. He believed that cold places produced emotionally distant people, and hot climates produced lazy, lethargic people. The ideal place (which coincidentally was his own place) was in the middle of the known world and produced the best kind of people. These ideas would now be considered environmentally deterministic. Remember that Environmental determinism is the idea that a particular landscape necessarily produces a certain kind of people. Ideas like this were still fashionable into the twentieth century. The problem with the idea is that it’s simplistic and reductionist. A cold environment doesn’t force people to be aloof. It forces them to invent warmer clothes. Technology is the difference, not behavior. Instead of determinism, the more common term to use is now possibilism. Physical landscapes set limits on a group of people that may or may not require a large adaptation, or a large modification of the environment itself. Humans can now survive in very inhospitable environments, most notably, the International Space Station.
Landscapes are cultural byproducts. The way that we use the local resources generates the visible landscape. Architecture, economic activities, clothing and entertainment are all visible to anyone interested in looking at a place. Because the physical landscape varies across space, and because culture varies across space, then the cultural landscape is variable as well. Different people can have different adaptations to similar places. Conversely, places far from one another may have similar adaptations to climate or other factors.
Cultural landscapes can be considered as both history and narrative. Power is written into the landscape. We make statues to commemorate the wealthy and the politically connected in rich places.  Looking at the landscape as a record of history, power, and representation is known as landscape-as-text. The landscape can be read in the same that a book can be read.
The largest differences between landscapes that we see now are the differences between the rural and the industrial and between places that are less integrated with the rest of the world and those that are heavily integrated (globalized). Global places are becoming homogenized.
Cultural Change
A sensible question to ask might be “Where did all the cultures come from?” As people moved into new places, they adapted and changed, and the new places were changed in turn. People change over time as well. Circumstances change in a place. Groups who move into a forest will need a to adapt if they cut down all the trees. Groups that adopt a new crop will see their lives change. Divergence could be as simple as borrowing a word to describe an invention. All cultures change.
Culture Regions
We can sort the world into regions based on cultural characteristics. A region is an area characterized by similarity or a cohesiveness that sets it apart from other regions. Regions are mental constructs, the lines between places are imaginary. When someone talks about the English-speaking world or Latin America, they are referring to culture regions.
4.2.1 Cultural Case Study: The Diffusion of Dancehall
A cultural attribute could diffuse just about anywhere, but that isn’t how diffusion usually works. Some places are interested in the innovation (new thing) and some are not. The following example takes one narrowly defined culturalattribute and traces a path to other places. Dancehall, a form of reggae, developed in Jamaica in the late 1970s and grew over time to prominence on the island. On of Jamaica’s main exports is music and Dancehall became an exported commodity like many other musical forms. In the case of Dancehall, the music is sufficiently defined to allow us to see where it has diffused to. Large markets like North America are visible to us and we see Dancehall in some of the music of Drake or Rihanna, but other places may seem less obvious. In Brazil, artists such as Lai Di Dai has taken the genre and adapted it to local tastes (which may or may not include changing the language of delivery).
In Germany, the band Seeed has found great success with Dancehall. And in Denmark we find artists like Raske Penge.
This musical style has moved far beyond its origin. Similar diffusion is found with other musical genres, from the earliest forms of pop music through to the present day.


9.4: Muscle Fiber Contraction and Relaxation
By the end of this section, you will be able to:
- Describe the components involved in a muscle contraction
- Explain how muscles contract and relax
- Describe the sliding filament model of muscle contraction
The sequence of events that result in the contraction of an individual muscle fiber begins with a signal — the neurotransmitter, acetylcholine (ACh) — from the motor neuron innervating that fiber. When an action potential traveling down the motor neuron arrives at the neuromuscular junction ACh is released from the axon terminal. These ACh molecules bind to receptors on the motor end plate (the specialized sarcolemma at the neuromuscular junction). This binding leads to the opening of sodium ion channels on the motor end plate and causes the sarcolemma to depolarize as positively charged sodium ions (Na + ) enter, triggering an action potential that spreads to the rest of the membrane, including the T-tubules. This triggers the release of calcium ions (Ca ++ ) from storage in the sarcoplasmic reticulum (SR). The Ca ++ then initiates contraction by binding to a thin filament regulatory protein (troponin) causing a molecular interaction that moves another thin filament regulatory protein (tropomyosin) off the myosin binding sites on actin. As soon as the myosin binding sites are exposed, myosin heads bind to actin and move through a “cross-bridge cycle”, that leads to muscle contraction (Figure \(\PageIndex{1}\)). As long as Ca ++ ions remain in the sarcoplasm to bind to troponin, which keeps the actin-binding sites “unshielded,” and as long as ATP is available to drive the cross-bridge cycling and the pulling of actin strands by myosin, the muscle fiber will continue to shorten to an anatomical limit.
Muscle contraction usually stops when signaling from the motor neuron ends, which repolarizes the sarcolemma and T-tubules, and closes the voltage-gated calcium channels in the SR. Ca ++ ions are then pumped back into the SR, through the process of active transport, which requires ATP. The lack of Ca ++ ions causes the tropomyosin to reshield (or re-cover) the binding sites on the actin strands, allowing the actin (thin) and myosin (thick) interaction to relax, ending the cross-bridge cycle. This leads to the muscle relaxing and lengthening. A muscle also can stop contracting when it runs out of ATP and becomes fatigued (Figure \(\PageIndex{2}\)).
The molecular events of muscle fiber shortening occur within the fiber’s sarcomeres (see Figure \(\PageIndex{3}\)). The contraction of a striated muscle fiber occurs as the sarcomeres, linearly arranged within myofibrils, shorten as myosin heads pull on the actin filaments.
The region where thick and thin filaments overlap has a dense appearance, as there is little space between the filaments. This zone where thin and thick filaments overlap is very important to muscle contraction, as it is the site where filament movement starts. Thin filaments, anchored at their ends by the Z-discs, do not extend completely into the central region that only contains thick filaments (H-zone), anchored at their bases at the M-line. A myofibril is composed of many sarcomeres running along its length; thus, myofibrils and muscle cells contract as the sarcomeres contract.
The Sliding Filament Model of Contraction
When signaled by a motor neuron, a skeletal muscle fiber contracts as the thin filaments are pulled and then slide past the thick filaments within the fiber’s sarcomeres. This process is known as the sliding filament model of muscle contraction (Figure \(\PageIndex{3}\)). The sliding can only occur when myosin-binding sites on the actin filaments are exposed by a series of steps that begins with Ca ++ entry into the sarcoplasm.
Tropomyosin is a protein that winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin. Tropomyosin binds to troponin , which anchors the tropomyosin in place, to form a troponin-tropomyosin complex. In a relaxed muscle, the troponin-tropomyosin complex prevents the myosin heads from binding to the active sites on the actin microfilaments. Troponin also has a binding site for Ca ++ ions.
These two regulatory proteins work together to respond to calcium and thus “regulate” sarcomere contraction. To initiate muscle contraction, the position of tropomyosin is shifted to expose the myosin-binding site on an actin filament to allow cross-bridge formation between the actin and myosin microfilaments. The first step in the process of contraction is for Ca ++ to bind to troponin causing an interaction that slides tropomyosin away from the binding sites on actin filaments. This allows the myosin heads to bind to these exposed binding sites and form cross-bridges. The thin filaments are then pulled by the myosin heads to slide past the thick filaments toward the center of the sarcomere. But each head can only pull a very short distance before it has reached its limit and must be “re-cocked” before it can pull again, a step that requires ATP.
ATP and The Cross-Bridge Cycle
For thin filaments to continue to slide past thick filaments during muscle contraction, myosin heads must pull the actin at the binding sites, detach, re-cock, attach to more binding sites, pull, detach, re-cock, etc. This repeated movement is known as the cross-bridge cycle. This motion of the myosin heads is similar to the oars when an individual rows a boat: The paddle of the oars (the myosin heads) pull, are lifted from the water (detach), repositioned (re-cocked) and then immersed again to pull (Figure \(\PageIndex{4}\)). Each cycle requires energy, and the action of the myosin heads in the sarcomeres repetitively pulling on the thin filaments also requires energy, which is provided by ATP.
Cross-bridge formation occurs when the myosin head attaches to actin while adenosine diphosphate (ADP) and inorganic phosphate (P i ) are still bound to myosin (Figure \(\PageIndex{4}\).a,b.). P i is then released, causing myosin to form a stronger attachment to the actin, after which the myosin head moves toward the M-line, pulling the actin along with it. As actin is pulled, the filaments move approximately 10 nm toward the M-line. This movement is called the power stroke , as movement of the thin filament occurs at this step (Figure \(\PageIndex{4}\).c.). In the absence of ATP, the myosin head will not detach from actin.
In addition to the actin binding sites on myosin heads, there is also an ATP binding site. When ATP binds in this location, it causes the myosin head to detach from the actin (Figure \(\PageIndex{4}\).d). After this occurs, ATP is converted to ADP and P i by the intrinsic ATPase activity of myosin. The energy released during ATP hydrolysis changes the angle of the myosin head into a cocked position (Figure \(\PageIndex{4}\).e). The myosin head is now in position for further movement.
When the myosin head is cocked, myosin is in a high-energy configuration. This energy is expended as the myosin head moves through the power stroke, and at the end of the power stroke, the myosin head is in a low-energy position. After the power stroke, ADP is released; however, the formed cross-bridge is still in place, and actin and myosin are bound together. As long as ATP is available, it readily attaches to myosin, the cross-bridge cycle can recur, and muscle contraction can continue.
Note that each thick filament of roughly 300 myosin molecules has multiple myosin heads, and many cross-bridges form and break continuously during muscle contraction. Multiply this by all of the sarcomeres in one myofibril, all the myofibrils in one muscle fiber, and all of the muscle fibers in one skeletal muscle, and you can understand why so much energy (ATP) is needed to keep skeletal muscles working. In fact, it is the loss of ATP that results in the rigor mortis observed soon after someone dies. With no further ATP production possible, there is no ATP available for myosin heads to detach from the actin-binding sites, so the cross-bridges stay in place, causing the rigidity in the skeletal muscles.
Relaxation of a Skeletal Muscle
Relaxing skeletal muscle fibers, and ultimately, the skeletal muscle, begins with the motor neuron, which stops releasing its chemical signal, ACh, into the synapse at the NMJ. The muscle fiber will repolarize, which closes the gates in the SR where Ca ++ was being released. ATP-driven pumps will move Ca ++ out of the sarcoplasm back into the SR. This results in the “reshielding” of the actin-binding sites on the thin filaments. Without the ability to form cross-bridges between the thin and thick filaments, the muscle fiber loses its tension and relaxes.
Muscle Strength
The number and type of skeletal muscle fibers in a given muscle is genetically determined and does not change. Muscle strength is directly related to the amount of myofibrils and sarcomeres within each fiber. Factors, such as hormones and stress (and artificial anabolic steroids), acting on the muscle can increase the production of sarcomeres and myofibrils within the muscle fibers, a change called hypertrophy, which results in an increased mass and bulk of a skeletal muscle. Likewise, decreased use of a skeletal muscle results in atrophy, where the number of sarcomeres and myofibrils decrease (but not the number of muscle fibers). It is common for a limb in a cast to result in dramatically atrophied muscles and certain diseases, such as polio, present with muscular atrophy as a comorbidity.
DISORDERS OF THE...
Muscular System
Duchenne muscular dystrophy (DMD) is a progressive weakening of the skeletal muscles. It is one of several diseases collectively referred to as “muscular dystrophy.” DMD is caused by a lack of the protein dystrophin, which helps the thin filaments of myofibrils bind to the sarcolemma. Without sufficient dystrophin, muscle contractions cause the sarcolemma to tear, causing an influx of Ca++, leading to cellular damage and muscle fiber degradation. Over time, as muscle damage accumulates, muscle mass is lost, and greater functional impairments develop.
DMD is an inherited disorder caused by an abnormal X chromosome. It primarily affects males, and it is usually diagnosed in early childhood. DMD usually first appears as difficulty with balance and motion, and then progresses to an inability to walk. It continues progressing upward in the body from the lower extremities to the upper body, where it affects the muscles responsible for breathing and circulation. It ultimately causes death due to respiratory failure, and those afflicted do not usually live past their 20s.
Because DMD is caused by a mutation in the gene that codes for dystrophin, it was thought that introducing healthy myoblasts into patients might be an effective treatment. Myoblasts are the embryonic cells responsible for muscle development, and ideally, they would carry healthy genes that could produce the dystrophin needed for normal muscle contraction. This approach has been largely unsuccessful in humans. A more recent approach has involved attempting to boost the muscle’s production of utrophin, a protein similar to dystrophin that may be able to assume the role of dystrophin and prevent cellular damage from occurring.
Concept Review
A muscle cell is filled with thousands of myofibrils, chains of sarcomeres attached from Z-disc to Z-disc. Sarcomeres are the smallest contractile portion of a muscle. Myofibrils are composed of thick and thin filaments. Thick filaments are composed of the protein myosin; thin filaments are composed of the protein actin. Troponin and tropomyosin are regulatory proteins affiliated with the thin filament.
Muscle contraction is described by the sliding filament model of contraction. ACh is the neurotransmitter that binds at the neuromuscular junction (NMJ) to trigger depolarization, and an action potential travels along the sarcolemma to trigger calcium release from the SR. The myosin binding sites on actin sites are exposed after calcium enters the sarcoplasm and activates the troponin-tropomyosin complex to shift. The latching of myosin heads docking onto actin-binding sites begins the “cross bridge cycle” a process that continues as long as calcium and ATP are present. During the “power stroke” myosin pulls thin filaments towards the M-line and as thin filaments slide over thick filaments, the Z-discs throughout a myofibril draw closer together to shorten the entire muscle fiber. Ultimately, the sarcomeres, myofibrils, and muscle fibers shorten to produce skeletal muscle contraction.
Review Questions
Q. In relaxed muscle, the myosin-binding site on actin is blocked by ________.
A. titin
B. troponin
C. myoglobin
D. tropomyosin
- Answer
-
Answer: D
Q. According to the sliding filament model, binding sites on actin open when ________.
A. creatine phosphate levels rise
B. ATP levels rise
C. acetylcholine levels rise
D. calcium ion levels rise
- Answer
-
Answer: D
Q. The cell membrane of a muscle fiber is called ________.
A. myofibril
B. sarcolemma
C. sarcoplasm
D. myofilament
- Answer
-
Answer: B
Q. Muscle relaxation occurs when ________.
A. calcium ions are actively transported out of the sarcoplasmic reticulum
B. calcium ions diffuse out of the sarcoplasmic reticulum
C. calcium ions are actively transported into the sarcoplasmic reticulum
D. calcium ions diffuse into the sarcoplasmic reticulum
- Answer
-
Answer: C
Q. During muscle contraction, the cross-bridge detaches when ________.
A. an ADP molecule binds to the myosin head
B. an ATP molecule binds to the myosin head
C. calcium ions bind to troponin
D. calcium ions bind to actin
- Answer
-
Answer: B
Q. Thin and thick filaments are organized into functional units called ________.
A. myofibrils
B. myofilaments
C. T-tubules
D. sarcomeres
- Answer
-
Answer: D
Critical Thinking Questions
Q. How would muscle contractions be affected if skeletal muscle fibers did not have T-tubules?
- Answer
-
A. Without T-tubules, action potential conduction into the interior of the cell would happen much more slowly, causing delays between neural stimulation and muscle contraction, resulting in slower, weaker contractions.
Q. What causes the striated appearance of skeletal muscle tissue?
- Answer
-
A. The microscopic arrangement of myofilaments within sarcomeres results in dark A bands and light I bands. These bands repeat along myofibrils, and the alignment of myofibrils in the cell cause the entire cell to appear striated.
Q. How would muscle contractions be affected if ATP was completely depleted in a muscle fiber?
- Answer
-
A. Without ATP, the myosin heads cannot detach from the actin-binding sites. All of the “stuck” cross-bridges result in muscle stiffness. In a live person, this can cause a condition like “writer’s cramps.” In a recently dead person, it results in rigor mortis.
Glossary
- aerobic respiration
- production of ATP in the presence of oxygen
- ATPase
- enzyme that hydrolyzes ATP to ADP
- creatine phosphate
- phosphagen used to store energy from ATP and transfer it to muscle
- glycolysis
- anaerobic breakdown of glucose to ATP
- lactic acid
- product of anaerobic glycolysis
- oxygen debt
- amount of oxygen needed to compensate for ATP produced without oxygen during muscle contraction
- power stroke
- action of myosin pulling actin inward (toward the M line)
- pyruvic acid
- product of glycolysis that can be used in aerobic respiration or converted to lactic acid
- troponin
- regulatory protein that binds to actin, tropomyosin, and calcium
- tropomyosin
- regulatory protein that covers myosin-binding sites to prevent actin from binding to myosin
Contributors and Attributions
-
OpenStax Anatomy & Physiology (CC BY 4.0). Access for free at https://openstax.org/books/anatomy-and-physiology


2.8: Summary and Conclusion
- 1. Read important passages again
- 2. Summarise parts of the text
- 3. Develop an argumentative structure
- 4. Write the essay
- 5. Look for typos
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After Knut read this WikiChapter he was relieved that he did not waste his time for the essay – quite the opposite! He now has a new view on problem solving – and recognises his problem as a well-defined one:
His initial state was the clear blank paper without any philosophical sentences on it. The goal state was just in front of his mind's eye: Him – grinning broadly – handing in the essay with some carefully developed arguments.
He decides to use the technique of Means-End Analysis and creates several subgoals:
Right after he hands in his essay Knut will go on reading this WikiBook. He now looks forward to turning the page over and to discovering the next chapter...


8.11F: Spirochaetes
- Outline the characteristics associated with spirochaetes and the associated diseases
The spirochaetes belong to a phylum of distinctive double-membrane bacteria that are characterized by their long, spiral-shaped cells. The spirochaetes are chemoheterotrophic in nature, free-living and capable of thriving in anaerobic environments. They are often distinguished from other bacterial phyla by the location of their flagella. The flagella, in spirochaetes, runs lengthwise between the inner and outer membranes in the periplasmic space. Often referred to as axial filaments, there is a twisting motion that occurs which allows the spirochaete to move. During reproduction, the spirochaete is capable of undergoing asexual reproduction via binary fission. The binary fission allows for production of two separate spirochaetes.
The spirochaetes can be divided into three families which include: Brachyspiraceae , Leptospiraceae , and Spirochaetaceae . These families are all categorized under a single order, Spirochaetales . There are specific species of spirochaetes that are considered to be pathogenic. Some of the pathogenic species include:
- Leptospira , the cause of leptospirosis – leptospirosis is transmitted to humans from animals and a common form of transmission is by allowing contaminated water to come in contact with unhealed breaks in the skin, eyes and mucous membranes. The water becomes contaminated by coming into contact with the urine of an infected animal.
- Borrelia burgdorferi, Borrelia garinii, Borrelia afzelii , the cause of lyme-disease
- Borrelia recurrentis , the cause of relapsing fever
- Treponema pallidum , subspecies pallidum , the cause of syphilis
- Treponema pallidum, subspecies pertenue , the cause of yaws (tropical infection of the skin, bones and joints)
- Brachyspira pilosicoli and Brachyspira aalborgi , the cause of intestinal spirochetosis
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- columnaris. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/columnaris . License : CC BY-SA: Attribution-ShareAlike
- Bacteroides biacutis 01. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Ba...iacutis_01.jpg . License : Public Domain: No Known Copyright
- Acidobacterium. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Acidobacterium.jpg . License : Public Domain: No Known Copyright
- Columnaris disease. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Co...is_disease.jpg . License : Public Domain: No Known Copyright
- Green sulfur bacteria. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Green_sulfur_bacteria . License : CC BY-SA: Attribution-ShareAlike
- Chlorobium. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Chlorobium . License : CC BY-SA: Attribution-ShareAlike
- Bacteroidetes. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Bacteroidetes . License : CC BY-SA: Attribution-ShareAlike
- photolithotropic. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/photolithotropic . License : CC BY-SA: Attribution-ShareAlike
- Bacteroides biacutis 01. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Ba...iacutis_01.jpg . License : Public Domain: No Known Copyright
- Acidobacterium. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Acidobacterium.jpg . License : Public Domain: No Known Copyright
- Columnaris disease. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Co...is_disease.jpg . License : Public Domain: No Known Copyright
- Green d winogradsky. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Gr...inogradsky.jpg . License : Public Domain: No Known Copyright
- Lemierre's syndrome. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Lemierre's_syndrome . License : CC BY-SA: Attribution-ShareAlike
- Fusobacteria. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Fusobacteria . License : CC BY-SA: Attribution-ShareAlike
- Fusobacterium. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Fusobacterium . License : CC BY-SA: Attribution-ShareAlike
- periodontal disease. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/periodontal+disease . License : CC BY-SA: Attribution-ShareAlike
- septicaemia. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/septicaemia . License : CC BY-SA: Attribution-ShareAlike
- asaccharolytic. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/asaccharolytic . License : CC BY-SA: Attribution-ShareAlike
- Bacteroides biacutis 01. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Ba...iacutis_01.jpg . License : Public Domain: No Known Copyright
- Acidobacterium. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Acidobacterium.jpg . License : Public Domain: No Known Copyright
- Columnaris disease. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Co...is_disease.jpg . License : Public Domain: No Known Copyright
- Green d winogradsky. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Gr...inogradsky.jpg . License : Public Domain: No Known Copyright
- Fusobacterium%20novum%2001. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Fu...m_novum_01.jpg . License : Public Domain: No Known Copyright
- Leptospirosis. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Leptospirosis . License : CC BY-SA: Attribution-ShareAlike
- Spirochaete. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Spirochaete . License : CC BY-SA: Attribution-ShareAlike
- periplasmic. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/periplasmic . License : CC BY-SA: Attribution-ShareAlike
- Bacteroides biacutis 01. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Ba...iacutis_01.jpg . License : Public Domain: No Known Copyright
- Acidobacterium. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Acidobacterium.jpg . License : Public Domain: No Known Copyright
- Columnaris disease. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Co...is_disease.jpg . License : Public Domain: No Known Copyright
- Green d winogradsky. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Gr...inogradsky.jpg . License : Public Domain: No Known Copyright
- Fusobacterium%20novum%2001. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Fu...m_novum_01.jpg . License : Public Domain: No Known Copyright
Key Points
- Spirochaetes are chemoheterotrophic in nature and capable of thriving in anaerobic conditions.
- The spirochaetes are categorized by the presence of axial filaments which run lengthwise between the inner and outer membranes in periplasmic space.
- Spirochaetes are capable of causing diseases including leptospirosis, Lyme disease, relapsing fever and syphilis.
Key Terms
- periplasmic : surrounding the plasma of a bacterium


19.4: Technical Investigations
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Platforms, Applications and Services
Addressing the role of information within cyberspace provides understanding for the rationale behind the design of ICTs such as knowledge management systems. To transition between the design of ICTs as a concept and the implementation of ICTs within the world of digital technology, we must establish a foundational understanding of the processes that occur in computer-to-computer interactions.
To begin this discussion, we must start with a computer. We tend to think about computers as those appliances that sit below our desk at home or office where we can check email or perhaps create a CV. In fact, the definition of a computer can encompass a huge variety of technology from Internet enabled cell phones to massive PBX (private branch eXchange) systems capable of supplying telephone service to over 20,000 users. The ability for computers to interact is based on the open system interconnection (OSI) model (or in a simplistic version referred to as the TCP / IP protocol stack).
An understanding of how computers interact does not necessarily require a detailed technical understanding of the underlying technology. It is important to understand, however, some basic terminology. First, the platform refers to the collective ability of software and hardware to provide general lower level and nonspecific functions for the user. One function of a platform is to allow for outputting data. On home computer systems, for example, the Microsoft Windows operating system enables the user to print information, or save it on disc. This functionality is provided by a combination of hardware and software that together is referred to as your (computer) platform.
Applications are directly tied to your platform. These applications provide the platform with the ability to provide task-specific functions by structuring the way the platform processes and presents data. Internet applications are designed to access information from the Internet in a defined manner. Microsoft Outlook, for example, is an application that is designed to send and receive digital mail. This application can access the functionality of the platform to display, store, or print the mail that has been received.
Web-based services provide data to applications in a format that is not dependent on the platform of the individual user. The ability to communicate between two computers is based on: the standardization that has occurred within the transportation of data across the physical network infrastructure, and the establishment of a common language (HTML for example). That is to say that standardization has created the ability to establish communication (through standardized packets sent by the TCP / IP protocol stack over network cabling) and communicate coherently (through sending and receiving HTML, XML, or other data).
Once computers have established communication, web-based services provide data for a specific application (the Skype Internet telephone service provides communication packaging through the voice over Internet protocol). The application is responsible for interpreting this data and sending it to the platform for processing. The platform then presents this information to the user in the appropriate format (based on the computer’s configuration). The Skype application, for example, would send and receive data from your Internet service provider and your computer platform, providing voice communication over the Internet through a headset and microphone.
Referencing and Recording Information
The independence of web services from platform-specific architecture can provide the ability to connect inherently different technologies. This ability to cross boundaries within system architecture, however, is not inherent in the technology. The technology has no inherent nature at all. The use of standardized communication packaging in no way requires the use of standardized languages. In fact, the ability to alter the way in which the computer interprets data is now a fundamental part of web services.
Altering how computers interpret data provides value by giving the application a structural context from which to view data that is received. By allowing the computer to maintain a specific and individual perspective, exploring complex relationships can be accomplished with greater efficiency. In the computer world, this individual perspective is based on a set of defined rules that allow the user to structure and reference information (much like colour-coded file folders and tabs are used to organize business information within a filing cabinet).
The explosion of new technology over the past twenty years has provided software developers with an overwhelming variety of tools for technological development. A quick tour of the computer section of the local book store will reveal volumes of books on C, C++, C#, Perl, Python, and PHP for programming; HTML, XML, XSL, and CSS for presentation / mark-up; and Flash, Illustrator, and Photoshop for graphic manipulation just to name a few. Each programming language has been used to create applications that store, retrieve and/or present information. Although a detailed review of these concepts is beyond the scope of this chapter, the information that follows will provide a valuable resource in this endeavour.
The technology infrastructure and management processes can provide information on the current state of organizational knowledge. Although measures for evaluating organizational knowledge would be imperfect at best, it would provide system administrators with the information to make system design decisions based on behavioural patterns. (Integrating process management tools with design models will be covered in greater detail later in the chapter). Once patterns are recognized, system functionality can be developed based on these patterns. From this perspective, internal referencing not only determines how individuals navigate through a computer application, if designed correctly, referencing can provide continuous feedback for identifying changing patterns of behaviour.
Referencing
While referencing, applied within an organization, can provide insight into managerial practices, sharing this information externally can be accomplished by creating policies regarding access to this information (and enforcing these policies through system design). The creation of policies can ensure that direct and indirect stakeholder interests have been addressed when distributing organizational information. Aside from the policies related to the management and use of information externally, the technical process that makes this communication feasible must also be considered.
Referencing and exchanging electronic data effectively requires locating and describing data efficiently. Describing data helps the user or program determine relevance, while structuring the data allows the user or program to locate the data quickly. Once located, relevant data can be recorded (saved to disk or printed), linked (bookmarked for direct access to web pages for example), or distributed (data can be published within web pages, through subscription news feeds, or printed and given away). Efficient access to data through referencing provides extraordinary power and potential within a networked environment.
Because of the large amounts of data available, accessing it efficiently has become increasingly important.. Several types of structural formatting rules have been established and are publicly available to developers for review. Examples of these structural formatting rules include document type definitions (or schemas) and older electronic data interchange (EDI) formats. These formatting rules are evolving and refining standards as developers build new features and capabilities into communication frameworks such as the eXtensible markup language (XML).
One reason that the XML framework has been enthusiastically adopted stems from its ability to structure information in a flexible manner, allowing information to be grouped into related sub-topics. This grouping is especially useful when relating complex information between various computer applications. Unlike hypertext markup language (which formats data), XML can be used for situating data within a hierarchal structure.
For example, the data “Jenn Arden Brown” would use HTML markup syntax ( … Jenn Arden Brown) to present the data in bold and italics: Jenn Arden Brown. XML markup would provide the semantic information (or field name in database terminology) used for adding context to the data using the following syntax:
<name>
<first>Jenn</first>
<middle>Arden</middle>
<last>Brown</last>
</name>
In this case, the data can be integrated into both internal and external applications (assuming the data structures exist). For example, Microsoft Outlook may recognize XML structured data from a cellular phone application and automatically offer to store the data located within the <name> node (and subsequent <first>, <middle>, and <last> nodes) into your list of personal contacts.
Recording
Referencing locates and describes data for computer applications. Recording is used to store data between references. Perhaps the simplest way to record data is through printing the data onto paper, creating a physical copy that can be filed away, faxed to outside offices, or published on information boards. In the age of digital information, however, the amount of data available makes printing impractical for storing large amounts of information.
Printing was used historically for the storage of all data required by physical machines during the infancy of the computer industry. Printing, as the predominant form of data storage, became outdated with the ability to reliably store information onto tape and disk technology. These three technologies are not completely dissimilar. Each requires information to be packaged and stored in a linear format. In fact, linear packaging of information (or serialization) is still the predominant method for recording information today. Image files (such as JPEG, BMP and MPEG), office documents (such as Word documents) and static HTML web pages all store information in a linear format. It is the responsibility of the application (web browser, photo editor, word processor) to read these files from start to finish, process the data, and present the information in a manner that can be understood by the user.
Although at a fundamental level all information within a computer is stored in a linear format, advances in computer applications have provided greater flexibility in the packing and unpacking process. The ability for applications to process data is determined by their ability to apply specific rules during this process. Photo editors, for example, can usually interpret JPEG, BMP, and GIF images. These file types use standardized rules for presenting images. These rules can be incorporated into applications that are designed for the Microsoft, Linux, or Macintosh operating systems. Applications such as Internet Explorer, Photoshop, and GIMP (Gnu Image Manipulation Program) read the files from start to finish, apply rules for interpreting the data, and display the result to the user. This process works fine for relatively small packages of data. Reading the entire contents within a file, however, quickly becomes impractical when searching large amounts of data (for example, you would not want to read a complete dictionary each time you needed to define a single word).
Because of these limitations, the ability to structure data began to evolve. One method used to structure information into manageable subgroups is to organize the data into horizontal rows (records) and vertical columns (fields). Using this structural format, it becomes possible to search through data that meets certain characteristics (such as all individuals with the first.name value of Jenn). This technique for structuring data is referred to as a database.
Previously, the XML framework was used to describe how information can be referenced between computers. Although XML does not store data, which is physically stored in a linear text file, XML is a data model that can provide hierarchal structure. To clarify this, we revisit the previous XML example:
<name>
<first>Jenn</first>
<middle>Arden</middle>
<last>Brown</last>
</name>
The data within this example is encapsulated within the tags <name> and </name>. In XML syntax, these tags can be described as opening and closing tags. In this case, the XML syntax references the node <name>, references the child node <first>, and inputs the data: Jenn. To externally reference (or exchange) this XML syntax with a database, we merely need to redefine how the computer application interprets the information. A database would interpret the XML syntax as follows:
| First | Middle | Last |
| Jenn | Arden | Brown |
Within a database, additional rows (termed records) can be used to describe a long list of people. When reading this database, the application can search only the ‘last’ field within the ‘name’ table and present only records with the data ‘Brown’ within this field. Searching within a single field reduces the amount of data that requires processing by applications. A relational data model, such as a database, requires that all records contain the same number of fields. Conversely, the XML data model is hierarchical, allowing unused nodes to be omitted. This differentiation will be explored in greater detail when technology development is discussed later in the chapter.
Organizing
We live in a hexi-deminal world, a reality where meaning is conveyed through characters (written and spoken) and numbers (pure and applied).
General numeric expressions like (3 x 2) or (3 + 2) can be used to help organize content [(6 people in 2 groups of 3) for example]. XML and related technologies (XSLT, XPath, XPointer) do not validate and/or execute more complex exponentiated functions. However, exponentiated functions [(2 to the power of 8) or the (square root of 64)] are generally excessive for organizing information into a coherent and flexible format easily read by humans.
In short, XML technology provides a fast and flexible data framework / model with an ability to transport complex and deeply encoded files for additional processing (like streaming video). This technology can be seen in practice in the virtual world Second Life where XML—Remote Procedure Calls provide complex social and visual interactions (like dancing, talking and flirting).
Although database standards like ODBC lack certain flexibilities, they are adept at defining strict relationships between data sources. These often complex relations are valuable when referencing and processing a large number of records. New initiatives (by QD Technology in particular) have shown that queries can be sent and processed (using standardized ODBC compliant instructions) with compiled database sources. Although there are still graphical limitations, this marks a significant development in the organization and portable distribution of content.


11.13: Light-Years
Yet trillions of miles to the nearest star beyond the Sun is not a measurement or system that is user-friendly. So astronomers use light-years instead. A light-year (ly) is a unit of length or distance; the distance light travels in one year. It is also written as light year or lightyear. So how does light travel in one year, or what is the length of a light-year? This sounds like a time calculation, and is often misused as such in movies, television shows, and books. The light-year is a distance measurement, and is calculated by knowing the speed of light.
Using light-years instead of miles, meters, or kilometers provides one a friendly number. For example, instead of stating the Sun is 93,000,000 miles away, one can note it is 8. 33 light minutes distance. What of Proxima Centauri, 25,219,301,250,000 miles or 40,586,533,727,000 kilometers away? Using light-years, Proxima Centauri is 4. 29 ly in distance.
To give you a sense of the size of our galaxy and even the Universe, there are about 30 stars, which lie within 16. 5 ly of Earth. Only 30 stars out of the billions of stars in just our own Milky Way galaxy.
Light Years: Calculations
Light-Years calculated in miles — the English System: 186,000 miles/second x 365. 25 days/year x 24 hours/day x 60 minutes/hour x 60 seconds/minute = 5,869,713,600,000 miles or 5. 8697136 x 10 12 miles
Light-Years calculated in meters and kilometers — the Metric System: 299,792,458 meters/second x 365. 25 days/year x 24 hours/day x 60 minutes/hour x 60 seconds/minute = 9,460,730,472,580,800 meters or 9.<PHONE_NUMBER>808 x 10 15 meters = 9,460,730,472,580. 8 kilometers 9.<PHONE_NUMBER>808 x 10 12 kilometers
Astronomical Units in 1 ly; distance from the Sun to Earth (93,000,000 miles = 1 AU): 1 ly = 63,241. 077 AU or 63241077 x 10 4 AU * *The distance light travels in one year is 63,241. 077 times the distance from Earth to Sun.


4.1: Introduction to Finding Secondary Sources
What you’ll learn to do: Evaluate and practice preliminary, intermediate, and advanced search techniques
Have you ever heard a song, made a mental note to look up its name, but then forgot all of the words? You remember wanting to hear it again and add it to your workout playlist, but all you remember is a short bit of the tune? How did you go about finding the song?
Chances are, you had to:
- Investigate to find out the song’s melody. Maybe you hummed the tune for a few friends, or remember that it sounded somewhat similar to another song you already heard, and used that song as a reference point.
- Investigate to find out the song’s title (“E.T.,” “The Lazy Song,” “Born This Way,” “Latinoamérica”).
- Investigate to find out who performed the song (Lady Gaga, Bruno Mars, Katy Perry, Maroon 5, Kanye West, Calle 13).
- Investigate to find out which album that song was on ( Teenage Dream, Doo-Wops & Hooligans, Born This Way, Entren Los Que Quieran ) and if there are other songs you might also enjoy.
- Investigate to find out where you can purchase or download the song for the best price.
You can’t—and won’t—get what you want without investigating . And it’s really no different with researching. Investigating is essential to your research because the questions you ask and the places you look will give you the results you need to create a convincing and compelling argument. Researching will take time and effort, so it pays off to take the time up front to learn about the best strategies for maximizing your research in order to identify and utilize the best sources. The wrong approach can waste your time and effort and result in a weak paper or report.
So, where do you start investigating? First, you’ll want to follow the research process. Once you have a good understanding of your research assignment and goals, you can begin to search for the right sources. In this section, you’ll learn how follow the research process in order to carefully use search engines and library databases to find articles you’ll need to write a top notch paper.
Contributors and Attributions
- Image of guitar. Authored by : erin m. Located at : https://flic.kr/p/8Fskd1 . License : CC BY-NC: Attribution-NonCommercial
- Pot of Gold Research Tutorial. Provided by : University of Notre Dame. Located at : library.nd.edu/instruction/potofgold/investigating/. License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
- Introduction to Finding Sources. Provided by : Lumen Learning. Located at : https://courses.lumenlearning.com/wm-englishcomposition1/chapter/outcome-finding-sources-3-1/ . License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike


9.1: Why It Matters- Inference for Two Proportions
Learning Objectives
- Recognize when to use a hypothesis test or a confidence interval to compare two population proportions or to investigate a treatment effect for a categorical variable.
- Determine if a study involving two proportions is an experiment or an observational study.
Why learn to make inferences about two populations?
In previous modules, we learned to make inferences about a population proportion. In particular, we learned the following:
- Random samples vary. When we use a sample proportion to make an inference about a population proportion, there is uncertainty. For this reason, inference involves probability.
- Under certain conditions, we can model the variability in sample proportions with a normal curve. We use the normal curve to make probability-based decisions about population values.
- We can estimate a population proportion with a confidence interval. The confidence interval is an actual sample proportion with a margin of error. We state our confidence in the accuracy of these intervals using probability.
- We can test a hypothesis about a population proportion using an actual sample proportion. Again, we base our conclusion on probability using a P-value. The P-value describes the strength of our evidence in rejecting a hypothesis about the population.
In Inference for Two Proportions , we continue to work with categorical data, so we continue to use proportions. But now we make inferences that compare two populations (or two treatments).
As an overview, consider again the Big Picture of Statistics.
Here we discuss the four steps in a statistical investigation for situations from Module 9.
- Produce Data: Determine what to measure, then collect the data . In this module, we collect categorical data from two samples. In an observational study, we begin with two populations and randomly select a sample from each population. In an experiment, we randomly assign individuals to two treatments. The use of random selection or random assignment allows us to view the samples as independent. This means we assume that the variable values from one sample do not influence the values for the other sample.
- Exploratory Data Analysis: Analyze and summarize the data . We are working with categorical data, so from each sample, we compute a sample proportion. To compare the two samples, we subtract the proportions. When we conduct inference in the next step, our goal is to to determine if the actual difference in the sample proportions is significantly different from what we expect in random sampling.
-
Draw a Conclusion:
Use data, probability, and statistical inference to draw a conclusion about the populations
.Our approach to inference repeats the reasoning we did in
Inference for One Proportion
.
- We use simulation to observe the behavior of the differences in sample proportions when we randomly select many, many samples. We create the simulation to reflect a claim about the populations. Then we develop a probability model to describe the shape, center, and spread of the sampling distribution. Of course, we are interested in the conditions that allow us to use a normal curve.
- We use this model to determine when a given difference is unusual in a formal hypothesis test.
- We also construct confidence intervals to estimate the difference between two population proportions. As before, we make a probability statement about our confidence in the accuracy of these intervals.
Example
The Abecedarian Early Intervention Project
In the 1970s, Abecedarian Early Intervention Project studied the long-term effects of early childhood education for poor children.
Research question: Does early childhood education increase the likelihood of college attendance for poor children?
- Produce Data: Determine what to measure, then collect the data. In this experiment, researchers selected 111 high-risk infants on the basis of the mothers’ education, family income, and other factors. They randomly assigned 57 infants to receive 5 years of high-quality preschool. The remaining 54 infants were a control group. All children received nutritional supplements, social services, and health care to control the effects of these confounding factors on the outcomes of the experiment.
- Exploratory Data Analysis: Analyze and summarize the data .By the age of 21 a much higher percentage of the treatment group enrolled in college, 42% vs. 20%.
- Draw a Conclusion: Use data, probability, and statistical inference to draw a conclusion about the populations .Is this difference statistically significant? In other words, is this difference due to the pre-school experience or due to chance? We will test the claim that a larger proportion of children who attend pre-school will attend college.
The following figure summarizes this investigation in the Big Picture.
Try It
Health Care for Non-Union and Union Workers
In a recent study the AFL/CIO selected random samples of non-union and union employees. They compared the proportion of workers in each sample who had health insurance. They found that the proportion of non-union workers with health insurance was significantly lower than the proportion of union workers with health insurance.
Contributors and Attributions
- Concepts in Statistics. Provided by : Open Learning Initiative. Located at : http://oli.cmu.edu . License : CC BY: Attribution