PS'' '' is an interactive

computer program A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangibl ...

for performing

statistical power In frequentist statistics, power is the probability of detecting a given effect (if that effect actually exists) using a given test in a given context. In typical use, it is a function of the specific test that is used (including the choice of tes ...

and sample size calculations. Dupont WD, Plummer WD: "Power and Sample Size Calculations: A Review and Computer Program", Controlled Clinical Trials 1990; 11:116-28.Dupont WD, Plummer WD: "Power and Sample Size Calculations for Studies Involving Linear Regression", Controlled Clinical Trials 1998; 19:589-601.

Program description

The P program can be used for studies with dichotomous, continuous, or survival response measures. The user specifies the

alternative hypothesis In statistical hypothesis testing, the alternative hypothesis is one of the proposed propositions in the hypothesis test. In general the goal of hypothesis test is to demonstrate that in the given condition, there is sufficient evidence supporting ...

in terms of differing response rates, means, survival times,

relative risk The relative risk (RR) or risk ratio is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. Together with risk difference and odds ratio, relative risk measures the association bet ...

s, or

odds ratio An odds ratio (OR) is a statistic that quantifies the strength of the association between two events, A and B. The odds ratio is defined as the ratio of the odds of event A taking place in the presence of B, and the odds of A in the absence of B ...

s. Matched or independent study designs may be used. Power, sample size, and the detectable alternative hypothesis are interrelated. The user specifies any two of these three quantities and the program derives the third. A description of each calculation, written in English, is generated and may be copied into the user's documents. Interactive help is available. The program provides methods that are appropriate for matched and independent t-tests, survival analysis,Schoenfeld DA, Richter JR: "Nomograms for Calculating the Number of Patients Needed for a Clinical Trial With Survival as an Endpoint" Biometrics 1982; 38:163-170. matchedDupont, WD: "Power Calculations for Matched Case-Control Studies", Biometrics, 1988; 44:1157-1168. and unmatchedCasagrande JT, Pike MC, Smith PG: "An Improved Approximate Formula for Calculating Sample Sizes for Comparing Two Binomial Distributions", Biometrics, 1978; 34:483-486.Schlesselman JJ: Case-control Studies: Design, Conduct, Analysis. New York: Oxford U. Press; 1982:144-152. studies of dichotomous events, the Mantel-Haenszel test,Wittes J, Wallenstein S: "The Power of the Mantel-Haenszel Test" J Am Stat Assoc, 1987; 82:1104-1109. and linear regression. The program can generate graphs of the relationships between power, sample size and the detectable alternative hypothesis. It can plot graphs of any two of these variables while holding the third constant. Linear or logarithmic axes may be used and multiple curves can be plotted on each graph. Graphs may be copied and pasted into other documents or programs for further editing.

Reviews

Reviews of this program have been published by McCrum-Gardner, Thomas and Krebs, Stawicki and Pezzullo.Pezzullo, JC: "Free Statistical Software

Retrieved August 28, 2013

Web version

A web-based version of the program is also available a
https://cqsclinical.app.vumc.org/ps/

References

External links

PS Webpage
* P3G, P³Gbr>: Public Population Project in Genomics and Society

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