Introduction. The standard deviation is a measure of the spread of scores within a set of data. Usually, we are interested in the standard deviation of a population. However, as we are often presented with data from a sample only, we can estimate the population standard deviation from a sample standard deviation.ntroduction. The standard deviation is a measure of the spread of scores within a set of data. Usually, we are interested in the standard deviation of a population. However, as we are often presented with data from a sample only, we can estimate the population standard deviation from a sample standard deviation.
Itching usually results from dry skin, a skin disorder, or an allergic reaction. If the person has no rash or skin abnormalities, the cause may be a drug, an allergic reaction that has internal effects, or a systemic disorder.
Dear Itchy, Hives, or urticaria, are a common condition that results in raised, red, and usually itchy patches of skin (wheals) that appear suddenly and then later disappear without a trace. They can appear all over the body, but usually appear first on the trunk and upper arms and legs, and most of the time they last anywhere from 24 hours to a couple of days. They can range in size from small dots the size of pencil tip to patches covering large areas of the body. Hives typically cause itching, stinging, or pain. Hives are one of the body's responses to the presence of histamine or other chemicals in the blood. They are often, but not always, caused by allergies. During an allergic reaction, the body recognizes a substance (e.g., foods, medications, new soaps, lotions, and perfumes, pollen, or animal hair) or a trigger as a dangerous intruder and mounts an immune response to it.