David C. Howell
This link is only barely started, and more will follow.
- If you want a whole set of variables with a specified set of correlations, check out the
response that David Nichols wrote in response to
such an inquiry.
- An complete implementation of David Nichols suggestion from the previous item can be
found at CorrGen2.html.
- For an example using multiple regression, look at a discussion of the relationship
between religious belief and optimism. This is based on a study by Sethi and Seligman, and is fairly
- An example built on a study by Geller, Johnston, and Madsen (1997)
contains a nice compilation of bits and pieces of multiple regression. It looks at
hierarchical regression, tolerance, interaction terms, and Baron and Kenny's (1986)
distinction between mediator and moderator effects.
- A topic of considerable interest these days is the analysis of interaction terms in
multiple regression. If the relationship between stress and illness itself depends on the
level of social support that the patient has, then the correct model would be of the form
Illness = b1*Stress + b2*SocSupp + b3*(Stress*SocSupp) + b0. A wonderful program to
illustrate this graphically is a freeware program called ITLASS. It can be found by going
to http://www.simstat.com. Check it out.
Return to Dave Howell's Statistical
Last revised: 10/26/01