(no cost)

Select the program name to download: RTM.EXE (73K)

The computer program, called RTM (regression toward the mean), generates a pretest and posttest for a group of persons. The user specifies the number of cases. Each score is based on one to four dice rolls, and all, some, or none of the dice rolls can be shared. The more dice shared, the greater the correlation. Negative correlations can be created by having the number of dice shared is negative. Also a number from one to four can be added to the pretest or the posttest. The data set can be stored for subsequent analysis.

The user controls the output from the program. Options include basic statistics, histograms, scatter plots, over-fitted regression lines, and Galton squeeze diagrams (see glossary for definitions). The over-fitted lines and the Galton squeeze diagrams are given forwards and backwards in time. The computer program is written in QuickBASIC and runs on IBM-compatible personal computers.

Examples of figures produced by RTM are contained on main and the description pages.