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Calculates Sample Size or Power for Matched Case-Control Studies

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

Description

sampsi_mcccalculates 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

samplesizein order to look at multiple calculations and to plot the results.

Updating this commandTo 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

Options

p0(#)specifies the exposure probability of controls; default isp0(0.5).

alt(#)specifies the "alternative OR".

n1(#)specifies the number of cases; default isn1(100).

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

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

power(#)power of test; default isp(0.9).

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

phi(#)specifies the correlation of exposure between pairs in the case-control set. The paper recommends the default value0.2when it is unknown.

ExamplesCalculate 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)

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

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

ReferenceDupont W.D. (1988) Power calculations for matched case-control studies. Biometr > ics 44: 1157-1168.

Related commands:See Alsosampsi, samplesize (if installed), sampclus (if installed), xsampsi (if installed), artmenu (if installed)