Using Microsoft Excel® to Calculate Descriptive Statistics and Create Graphs

Descriptive statistics and appropriate visual representations of scores are important for all test developers, whether they are experienced testers working on large-scale projects, or novices working on small-scale local tests. Many teachers put in charge of testing projects do not know why they are important, however, and are utterly convinced that they lack the mathematical ability to address the matter anyway. This article begins by explaining why descriptives need to be calculated in the first place, and then discusses ways in which to display data visually, and how to do this using Microsoft Excel (R) spreadsheet software. The article then addresses three types of descriptive statistics: measures of central tendency, measures of dispersion, and indicators of the shape of the distribution. It discusses some basic points about interpreting them and then provides simple instructions for calculating them in Excel. The article assumes that readers are not particularly familiar with Excel and does not assume a high level of mathematical sophistication.