-- PeterBacchetti - 21 Jun 2012

Numeric Variable

This is a variable that is measured as a number on a quantitative scale, such as weight in kilograms or age in years. Counts, such as the number of hospital-acquired infections over a one year period, are also numeric variables. (There are specialized analysis methods for count variables.)

Sometimes a categorical variable is treated as numeric for purposes of statistical analysis. If the categories are ordered, then a numeric value can be assigned to each category. For example, responses of strongly disagree, disagree, neutral, agree, and strongly agree, could be assigned values of -2, -1, 0, 1, and 2, permitting the variable to be analyzed as numeric. The numbers assigned are usually consecutive integers, but this is an arbitrary choice and alternatives may be more appropriate in some cases.

Conversely, numeric variables can be analyzed as categorical by grouping them, for example into quartiles. Sometime more natural groupings are used, such as age grouped into 20-29, 30-39, 40-49, etc.