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.
Itching all over is an annoying sensation often caused by skin irritation or inflammation. Itching all over may be associated with a rash or other skin symptoms, or it may occur by itself.Itching all over can be caused by a relatively mild condition, such as dry skin and a build-up of dead skin cells.For example, if you feel itchy all over and you live in a dry climate, you may have âwinter itchâ caused by the lack of moisture in your skin.tching all over is an annoying sensation often caused by skin irritation or inflammation. Itching all over may be associated with a rash or other skin symptoms, or it may occur by itself.