help for sampsi_mcc

Calculates Sample Size or Power for Matched Case-Control Studies

sampsi_mcc [, p0(#) alt(#) n1(#) m(#) phi(#) alpha(#) power(#) solve(string) } ]


sampsi_mcc calculates the power and sample size for a matched case control study. The theory behind this command is described in Dupont (1988) Power Calculations for Matched Case-Control Studies, Biometrics.

The calculations require the usual alpha and beta values, a possible alternative odds ratio (the null is 1), phi the correlation of exposure between pairs in the case-control set (the default is 0.2) and the probability of exposure in the controls.

This command can be combined with samplesize in order to look at multiple calculations and to plot the results.

Updating this command

To obtain the latest version click the following to uninstall the old version ssc uninstall sampsi_mcc And click here to install the new version ssc install sampsi_mcc


p0(#) specifies the exposure probability of controls; default is p0(0.5).

alt(#) specifies the "alternative OR".

n1(#) specifies the number of cases; default is n1(100).

m(#) specifies the number of matched controls per case; default is m(1).

alpha(#) significance level of test; default is a(0.05).

power(#) power of test; default is p(0.9).

solve(string) specifies whether to solve for the sample size or power; default is s(n) solves for n and the only other choice is s(power) solves for power.

phi(#) specifies the correlation of exposure between pairs in the case-control set. The paper recommends the default value 0.2 when it is unknown.


Calculate power for a two-sided test:

sampsi_mcc, p0(0.5) alt(1.5) n(100) s(power)

Compute sample size:

sampsi_mcc, p0(0.5) alt(1.5) s(n)

Compute sample size when the power is 80%:

sampsi_mcc, p0(0.5) alt(1.5) s(n) power(0.8)

Re-calculate the above values for 5 matched controls rather than 1:

sampsi_mcc, p0(0.5) alt(1.5) n(100) s(power) m(5)

Compute sample size:

sampsi_mcc, p0(0.5) alt(1.5) s(n) m(5)


Adrian Mander, MRC Human Nutrition Research, Cambridge, UK.

Email adrian.mander@mrc-hnr.cam.ac.uk


Dupont W.D. (1988) Power calculations for matched case-control studies. Biometr > ics 44: 1157-1168. See Also Related commands:

sampsi, samplesize (if installed), sampclus (if installed), xsampsi (if installed), artmenu (if installed)