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Sample size determinations using logistic regression with pilot data.

V F Flack·T L Eudey
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Abstract

Suppose the goal of a projected study is to estimate accurately the value of a 'prediction' proportion p that is specific to a given set of covariates. Available pilot data show that (1) the covariates are influential in determining the value of p and (2) their relationship to p can be modelled as a logistic regression. A sample size justification for the projected study can be based on the logistic model; the resulting sample sizes not only are more reasonable than the usual binomial sample size values from a scientific standpoint (since they are based on a model that is more realistic), but also give smaller prediction standard errors than the binomial approach with the same sample size. In appropriate situations, the logistic-based sample sizes could make the difference between a feasible proposal and an unfeasible, binomial-based proposal. An example using pilot study data of dental radiographs demonstrates the methods.

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Confidence IntervalsHumansLogistic ModelsMethodsPilot ProjectsProbabilityRadiography, DentalSampling StudiesJournal Article

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V F Flack, T L Eudey. 1993-06-15. Sample size determinations using logistic regression with pilot data.. https://doi.org/10.1002/sim.4780121107

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