What is an example of a continuous variable?

A continuous variable is one that can take on an infinite number of values within a given range and is often measured rather than categorized. Tumor size is a prime example of a continuous variable because it can be measured in various ways, such as in millimeters or centimeters, and can take any value within a plausible range. For instance, a tumor could be 1.3 cm, 2.7 cm, or 3.9 cm, demonstrating that it can have decimal points and not be confined to discrete categories.

In contrast, gender, religion, and smoker status are categorical variables. Gender refers to defined categories such as male and female, and religion also consists of distinct categories such as Christian, Muslim, or Hindu. Smoker status is typically dichotomous—either a person is considered a smoker or a non-smoker. These variables do not have values that can be measured on a continuous scale, which is essential for distinguishing continuous variables from categorical ones. Thus, tumor size stands out as the correct example of a continuous variable in this context.