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help for sampsi_mcc
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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_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

Options

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.

Examples

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)

Author

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

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

Reference

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)