Linked Life Data

7569499

Source:http://linkedlifedata.com/resource/pubmed/id/7569499

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
9-10
pubmed:dateCreated
1995-10-26
pubmed:abstractText
The sample size for a trial depends on the type I and type II error rates and on the minimum relevant clinical difference, all of which are known, and on the anticipated, but unknown, value of a measure of variation for the key response. This measure is the overall response rate when the key response is binomially distributed, or the residual variance in each treatment group when the key response is continuous and normally distributed. Since the true value of the measure is unknown, it must be guessed or estimated from previous trials. We describe approaches to determine an appropriate value for it, both before the trial begins and after it has begun, for use in calculating the final sample size. These approaches differ from previously described 'internal pilot' methods in not requiring unblinding of the treatment assignments in the trial. They preserve the power and do not affect the type I error rate materially. The approaches can be applied to longitudinal studies where the rate of change over time is the response of interest, and to group sequential trials.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:issn
0277-6715
pubmed:author
pubmed:issnType
Print
pubmed:volume
14
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1039-51; discussion 1053-5
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:articleTitle
Planning and revising the sample size for a trial.
pubmed:affiliation
Merck Research Laboratories, West Point, PA 19486, USA.
pubmed:publicationType
Journal Article, Review