Thanks to Kit Baum, a new package swpermute is now downloadable from SSC. To install the package type:
The swpermute package conducts permutation tests for stepped-wedge cluster-randomised trials, but could also be used for other cluster-randomised trial designs. Permutation tests are useful in stepped-wedge trials to provide robust statistical tests of intervention effect estimates. Stata's permute command does not provide valid p-values for these trial designs because individual observations are not exchangeable. To overcome this, the clusters must be permuted rather than the individual observations.
The command provides additional functionality to aid users in performing analyses of stepped-wedge trials. We include the option withinperiod that performs the specified analysis separately in each period of the study and the resulting period-specific intervention effect estimates are combined as a weighted average. This is sometimes also known as a vertical analysis. We include the option null to test non-zero null hypothesis values in order to construct confidence intervals.
The syntax is similar to the syntax used for Stata's permute command, with some additional required options to describe the trial design. There is also a dialog box available fro this command; details on how to add this menu are given in the command help file.
Best wishes
Jennifer Thompson
Code:
ssc install swpermute help swpermute
The command provides additional functionality to aid users in performing analyses of stepped-wedge trials. We include the option withinperiod that performs the specified analysis separately in each period of the study and the resulting period-specific intervention effect estimates are combined as a weighted average. This is sometimes also known as a vertical analysis. We include the option null to test non-zero null hypothesis values in order to construct confidence intervals.
The syntax is similar to the syntax used for Stata's permute command, with some additional required options to describe the trial design. There is also a dialog box available fro this command; details on how to add this menu are given in the command help file.
Best wishes
Jennifer Thompson
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