These include the program PS which is described by Dupont and Plummer (1990) and available at ) and Open Epi which can be downloaded from. The POWER and GLMPOWER procedures in the statistical analysis program package SAS can handle sample size calculations for a range of situations, including survival analy- sis, as can the PASS module (a trial version of which is available at ).Ī variety of free sample size calculators may be found on the Internet. The sample size formulae used by this package differ slightly from those presented in this book, but the results should be quite similar in most cases. The command allows for different sample sizes in the two trial arms. Alternatively, if the chosen sample sizes are entered, the user can determine the power that these will provide. The sampsi command in Stata allows the user to obtain the required sample size for the comparison of means or proportions. Here we mention three packages which readers may find helpful when planning field trials.
Most statistical packages have some provision for sample size calculations. This can be particularly helpful when a large number of cal- culations need to be carried out, for example, to explore sample size requirements for different outcomes or under different assumptions, or to produce power curves.
#Statcalc free download software#
However, computer software is also available to carry out some of these calculations. Most of the formulae given in this chapter are simple enough to do by hand, with the aid of a simple calculator.
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