Once we have the data laid out and a feel for what’s in there, we can start describing the variables. The first thing to do is get some overall measure of the ‘‘typical’’ value for each variable. This is called a measure of central tendency.

The three most widely used measures of central tendency are the mode, the median, and the mean. All these get packaged together in everyday speech as some kind of ‘‘average,’’ but we have to be more precise in data analysis. Each measure of central tendency carries important information about the values of a variable.

Here are the definitions for each of these measures of central tendency:

1. The mode is the attribute of a variable that occurs most frequently. The mode can be found for nominal-, ordinal-, and interval-level variables, but it is the only measure of central tendency available for nominal variables.

2. The median is the midpoint in a distribution above and below which there are an equal number of scores in a distribution. The median can be found for ordinal- and interval- level variables.

3. The mean, or the average, is the sum of the individual scores in a distribution, divided by the number of scores. The mean can be found for ordinal- and interval-level variables.