August 7, 2009
toward the Mean
program name to download: RTM.EXE
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.
back to the primer page.