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On the use of a pilot sample for sample size determination
Author(s) -
Browne Richard H.
Publication year - 1995
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.4780141709
Subject(s) - sample size determination , statistics , sample (material) , monte carlo method , standard deviation , confidence interval , sigma , power (physics) , mathematics , population , standard error , econometrics , medicine , physics , environmental health , quantum mechanics , thermodynamics
To compute the sample size needed to achieve the planned power for a t ‐test, one needs an estimate of the population standard deviation δ. If one uses the sample standard deviation from a small pilot study as an estimate of δ, it is quite likely that the actual power for the planned study will be less than the planned power. Monte Carlo simulations indicate that using a 100(1 − γ) per cent upper one‐sided confidence limit on δ will provide a sample size sufficient to achieve the planned power in at least 100(1 − γ) per cent of such trials.