Home LiteratureArticle Details

PMID: 7580713 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't Review

Estimating sample sizes for binary, ordered categorical, and continuous outcomes in two group comparisons.

BMJ (Clinical research ed.) ·Vol. 311 ·No. 7013 ·1995-10-28 ·Pages 1145-8

Campbell MJ, Julious SA, Altman DG

Abstract

Sample size calculations are now mandatory for many research protocols, but the ones useful in common situations are not all easily accessible. This paper outlines the ways of calculating sample sizes in two group studies for binary, ordered categorical, and continuous outcomes. Formulas and worked examples are given. Maximum power is usually achieved by having equal numbers in the two groups. However, this is not always possible and calculations for unequal group sizes are given.

MeSH Terms

Data Interpretation, Statistical Humans Sample Size

Authors & Affiliations

3 authors, click to expand affiliations / ORCID

Campbell M J

Medical Statistics and Computing, University of Southampton, Southampton General Hospital.

Julious S A

Altman D G

References (17)

17 references, click to expand

The importance of beta, the type II error and sample size in the design and interpretation of the randomized control trial. Survey of 71 "negative" trials.
N Engl J Med. 1978 Sep 28;299(13):690-4 PMID: 355881
Introduction to sample size determination and power analysis for clinical trials.
Control Clin Trials. 1981 Jun;2(2):93-113 PMID: 7273794
Approaches to sample size estimation in the design of clinical trials--a review.
Stat Med. 1984 Jul-Sep;3(3):199-214 PMID: 6385187
Use of check lists in assessing the statistical content of medical studies.
Br Med J (Clin Res Ed). 1986 Mar 22;292(6523):810-2 PMID: 3082452
Indexes and boundaries for "quantitative significance" in statistical decisions.
J Clin Epidemiol. 1990;43(12):1273-84 PMID: 2254764
Confidence intervals and sample sizes: don't throw out all your old sample size tables.
BMJ. 1991 Feb 9;302(6772):333-6 PMID: 2001510
Sample size estimation for comparing two or more treatment groups in clinical trials.
Stat Med. 1991 Jan;10(1):33-43 PMID: 2006354
Sixteen S-squared over D-squared: a relation for crude sample size estimates.
Stat Med. 1992 Jun 15;11(8):1099-102 PMID: 1496197
Management of feverish children at home.
BMJ. 1992 Nov 7;305(6862):1134-6 PMID: 1463951
Sample size for beginners.
BMJ. 1993 May 1;306(6886):1181-4 PMID: 8499826
Relation of fingerprints and shape of the palm to fetal growth and adult blood pressure.
BMJ. 1993 Aug 14;307(6901):405-9 PMID: 8374451
Condoms: a wider range needed.
BMJ. 1993 Oct 16;307(6910):987 PMID: 8241912
Sample size calculations for ordered categorical data.
Stat Med. 1993 Dec 30;12(24):2257-71 PMID: 8134732
Statistical power, sample size, and their reporting in randomized controlled trials.
JAMA. 1994 Jul 13;272(2):122-4 PMID: 8015121
Planning for precision in survival studies.
J Clin Epidemiol. 1994 Nov;47(11):1277-85 PMID: 7722564
Can there be a more patient-centred approach to determining clinically important effect sizes for randomized treatment trials?
J Clin Epidemiol. 1994 Jul;47(7):787-95 PMID: 7722592
Sample size: how many patients are necessary?
Br J Cancer. 1995 Jul;72(1):1-9 PMID: 7599035

Article Info

Journal

BMJ (Clinical research ed.)

Abbr.

BMJ

ISSN

0959-8138

DOI

10.1136/bmj.311.7013.1145

Published

1995-10-28

Pages

1145-8

Language

English

Region

England

NLM ID

8900488

PMCID

PMC2551061

Subset

Corrections

ErratumIn

External Links

PubMed source DOI: 10.1136/bmj.311.7013.1145 PMC Full Text

Analysis Services

Estimating sample sizes for binary, ordered categorical, and continuous outcomes in two group comparisons.

Contact

WeChat Official Account