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Random Variable

  • In: Encyclopedia of Epidemiology
  • Edited by: Sarah Boslaugh
  • Subject:Public Health (general), Public Health Research Methods , Epidemiology & Biostatistics

A variable whose observed values may be considered as outcomes of a stochastic or random experiment is called a random variable. The values of such a variable in a particular sample cannot be anticipated with certainty before the sample is gathered. Random variables are commonly classified as qualitative or categorical, discrete, or continuous.

A random variable is defined as a qualitative or categorical variable if its set of possible values do not represent numerical information. For example, gender is a categorical variable. Suppose that among 100 patients, there are 65 females and 35 males, and let X be the sex of a randomly chosen patient among these 100 patients. Then X is a qualitative random variable, and the values of X are ‘Female’ and ‘Male’ ...

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