How Appropriate are Popular Sample Size Formulas?
作者:
LawrenceL. Kupper,
KerryB. Hafner,
期刊:
The American Statistician
(Taylor Available online 1989)
卷期:
Volume 43,
issue 2
页码: 101-105
ISSN:0003-1305
年代: 1989
DOI:10.1080/00031305.1989.10475628
出版商: Taylor & Francis Group
关键词: Confidence interval width;Power;tdistribution
数据来源: Taylor
摘要:
One concern in the early stages of study planning and design is the minimum sample size needed to provide statistically credible results. This minimum sample size is usually determined via the use of simple formulas or, equivalently, from tables. The more popular formulas, however, involve large-sample approximations and hence may underestimate required sample sizes. This article provides empirical evidence indicating that this underestimation phenomenon is extreme for certain sample size formulas based on confidence interval width. Common sample size formulas that consider statistical power are also discussed; these are shown to perform quite well, even for small sample size situations.
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