Question

how can the use of a restricted rather than random sample affect the outcome of analysis?

Answer 1

Solution:

Although the odds raho is a useful measure of strength of association between two dichotomous random vanables, provides a valid estimate of the magnitude of the effect only if the sample of observations on which is based is random

This point is somehmes forgotten, a regncted sample, such as a sample of patients from a single hospital s usually much easier to obtain

This restricted sample is then used to make inference about the population as a whole As a nesult the researchers observe an association that does not actually exist.

This kind of spurious relationship among variables which is evident only because of the way in which Me sample was chosen is known as Berks.'s allacy
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