We provide a program to illustrate interactions between treatment and covariates or between two covariates by using forest plots under either the Cox proportional hazards or the logistic regression model. The program is flexible in both the possibility of illustrating more than one interaction at a time and variable specifications of scale.
BartelsL. M.2000. Partisanship and voting behavior, 1952–1996. American Journal of Political Science44: 35–50.
2.
GailM., and SimonR.1985. Testing for qualitative interactions between treatment effects and patient subsets. Biometrics41: 361–372.
3.
HosmerD. W.Jr., and LemeshowS.2000. Applied Logistic Regression. 2nd ed. New York: Wiley.
4.
HoutM.1984. Status, autonomy, and training in occupational mobility. American Journal of Sociology89: 1379–1409.
5.
LewisS., and ClarkeM.2001. Forest plots: Trying to see the wood and the trees. British Medical Journal322: 1479–1480.
6.
MareR. D.1991. Five decades of educational assortative mating. American Sociological Review56: 15–32.
7.
PetersonB., and GeorgeS. L.1993. Sample size requirements and length of study for testing interaction in a 1 x k factorial design when time-to-failure is the outcome. Controlled Clinical Trials14: 511–522.
8.
RaffnE., MikkelsenS., AltmanD. G., ChristensenJ. M., and GrothS.1988. Health effects due to occupational exposure to cobalt blue dye among plate painters in a porcelain factory in Denmark. Scandinavian Journal of Work and Environmental Health14: 378–384.
9.
ShusterJ., and van EysJ.1983. Interaction between prognostic factors and treatment. Controlled Clinical Trials4: 209–214.
10.
SimonR.2002. Bayesian subset analysis: Application to studying treatment-by-gender interactions. Statistics in Medicine21: 2909–2916.
11.
ThallP. F., and LachinJ. M.1986. Assessment of stratum–covariate interactions in Cox's proportional hazards regression model. Statistics in Medicine5: 73–83.
12.
UesakaH.1993. Test for interaction between treatment and stratum with ordinal responses. Biometrics49: 123–129.
13.
UlmK., SchmoorC., SauerbreiW., KemmlerG., AydemirU., MuellerB., and SchumacherM.1989. Strategien zur auswertung einer therapiestudie mit der ueberlebenszeit als zielkriterium. Biometrie und Informatik in Medizin und Biologie20: 171–205.
14.
XiangA., SatherH., and AzenS.1994. Power considerations for testing an interaction in a 2 x k factorial design with a failure time outcome. Controlled Clinical Trials15: 489–502.
