Critique Ways in Which Data is Presented

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Critique Ways in Which Data is Presented Powered By Docstoc
					Main Resource: Statistics Canada
 You  have probably heard of the term the
  information age. It describes how modern
  society depends on information as a
  resource. People rely on information to make
  decisions and recommendations in many
  fields, including politics, economics,
  environment and entertainment.
 Without reliable information, people can
  make poor decisions that sometimes result in
  serious consequences.
 Since the media plays an immense part in our
  daily life and they are continually giving us
  information (data).
 Data analysis is often used in advertising,
  forecasting, and public policy. The media is full
  of representations of data (i.e. Graphs or tables)
  to support statistical claims.
 We need to be critical to:
     Know what is relevant
     Know what is important
     Know what is true
     Know what is biased
     Identify misinformation
     Etc.
A   graph is a visual representation of a
  relationship between, but not restricted to,
  two variables.
 Graphs are effective visual tools because
  they present information quickly and easily.
  It is not surprising then, that graphs are
  commonly used by print and electronic
 Circle graphs
 Line graphs
 Bar graphs
 Double bar graphs
 Pictographs
A circle graph displays data as a percentage
 of the whole. Each pie section should have a
 label and percentage. A total data number
 should be included.
A line graph plots continuous data as points
 and then joins them with a line. Multiple
 data sets can be graphed together, but a key
 must be used.
A bar graph displays discrete data in separate
 columns. A double bar graph can be used to
 compare two data sets. Categories are
 considered unordered and can be rearranged
 alphabetically, by size, etc.
A pictograph uses an icon to represent a
 quantity of data values in order to decrease
 the size of the graph. A key must be used to
 explain the icon.
 Misinterpretation  is a common problem when
 using statistical information. It may be
 caused by a number of factors.
    Misunderstanding the data
    Using incomparable definitions
    Deliberately misinterpreting the information
 In groups of 2 or 3, come get a worksheet
  and answer the questions.
 You will need to prepare a short presentation
  about your topic (based on your worksheet)
  to present to the class.
 Advantages
    Visually appealing
    Shows percent of total for each category
 Disadvantages
    No exact numerical data
    Hard to compare 2 data sets
    "Other" category can be a problem
    Total unknown unless specified
    Best for 3 to 7 categories
    Use only with discrete data
 Advantages
    Can compare multiple continuous data sets easily
    Interim data can be inferred from graph line
 Disadvantages
    Use only with continuous data
 Advantages
    Visually strong
    Can easily compare two or three data sets
 Disadvantages
    Graph categories can be reordered to emphasize
     certain effects
    Use only with discrete data
 Advantages
    Easy to read
    Visually appealing
    Handles large data sets easily using keyed icons
 Disadvantages
    Hard to quantify partial icons
    Icons must be of consistent size
    Best for only 2-6 categories
    Very simplistic
Look at the effect of not starting
the y-axis of 0.

It is important to start graphs at
Look at this pictograph. It looks like there are more horses. It is
important that all the pictures are the same size.
Why does Graph A look different than Graph B? Both the
graphs represent the same data.
The graphs look different due to the
different vertical scales. Graph A appears
to show a more rapid decrease in sales
than graph B.

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