TITLE: `METAPOW' : module for simulation based sample size calculations for designing new clinical trials and diagnostic
test accuracy studies to update an existing meta-analysis.

DESCRIPTION/AUTHOR:
The metapow package contains a suite of programs which enable the user to estimate the probability the conclusions 
of a meta-analysis will change with the inclusion of a new study(ies). Using the -metasim- program, a simulation 
approach to estimating the effects in future studies is taken. The method assumes that the effect sizes of future 
studies are consistent with those observed previously, as represented by the current meta-analysis. 
Both the contexts of two-arm randomised controlled trials and studies of diagnostic test accuracy are considered 
for a variety of outcome measures.  Calculations are possible under both fixed and random effect assumptions and 
several approaches to inference including statistical significance and limits of clinical significance are possible. 
Calculations for specific sample sizes can be conducted (using -metapow-), and plots, akin to traditional power 
curves, indicating the probability a new study(ies) will change inferences for a range of sample sizes can be produced 
(using -metapowplot-). We hope the package will be useful to i) trialists who want to assess the impact potential new 
trials will have on the overall evidence base; and ii) meta-analysts who want to assess the robustness of the 
current meta-analysis to the inclusion of future data.

Keywords: meta-analysis, simulation, sample size, evidence based medicine

Author: Michael J. Crowther, University of Leicester
Support: email michael.crowther@le.ac.uk

Author: Sally R. Hinchliffe, University of Leicester
Support: email srh20@le.ac.uk

Requires: Stata version 11.2