When constructing a histogram, you first make a distribution table , which shows the number of subjects in each class interval. Pay attention to the idea of endpoint convention, which tells you what to do with individuals who fall exactly on the edge of a class interval. Sections 1 through 3 provide detailed examples to help you understand how to read and draw a histogram. As a self-test, work exercise set B and exercise C 3. The answers appear in the text's appendix.
Variables are characteristics that change from subject to subject in a study.
Quantitative variables are further classified as discrete or continuous . A discrete variable takes on values that differ by fixed amounts. A continuous variable can have arbitrarily small differences between subjects. Time, height, and weight are examples of continuous variables. Recall from the last chapter that there can be more than one factor of interest in a study.