Journal article
Monte Carlo Simulations Comparing Fisher Exact Test and Unequal Variances t Test for Analysis of Differences Between Groups in Brief Hospital Lengths of Stay
Anesthesia and analgesia, Vol.125(6), pp.2141-2145
12/2017
DOI: 10.1213/ANE.0000000000002428
PMID: 28961563
Abstract
We examined type I and II error rates for analysis of (1) mean hospital length of stay (LOS) versus (2) percentage of hospital LOS that are overnight. These 2 end points are suitable for when LOS is treated as a secondary economic end point. We repeatedly resampled LOS for 5052 discharges of thoracoscopic wedge resections and lung lobectomy at 26 hospitals. Unequal variances t test (Welch method) and Fisher exact test both were conservative (ie, type I error rate less than nominal level). The Wilcoxon rank sum test was included as a comparator; the type I error rates did not differ from the nominal level of 0.05 or 0.01. Fisher exact test was more powerful than the unequal variances t test at detecting differences among hospitals; estimated odds ratio for obtaining P < .05 with Fisher exact test versus unequal variances t test = 1.94, with 95% confidence interval, 1.31-3.01. Fisher exact test and Wilcoxon-Mann-Whitney had comparable statistical power in terms of differentiating LOS between hospitals. For studies with LOS to be used as a secondary end point of economic interest, there is currently considerable interest in the planned analysis being for the percentage of patients suitable for ambulatory surgery (ie, hospital LOS equals 0 or 1 midnight). Our results show that there need not be a loss of statistical power when groups are compared using this binary end point, as compared with either Welch method or Wilcoxon rank sum test.
Details
- Title: Subtitle
- Monte Carlo Simulations Comparing Fisher Exact Test and Unequal Variances t Test for Analysis of Differences Between Groups in Brief Hospital Lengths of Stay
- Creators
- Franklin DexterEmine O BaymanElisabeth U Dexter
- Resource Type
- Journal article
- Publication Details
- Anesthesia and analgesia, Vol.125(6), pp.2141-2145
- Publisher
- United States
- DOI
- 10.1213/ANE.0000000000002428
- PMID
- 28961563
- ISSN
- 0003-2999
- eISSN
- 1526-7598
- Language
- English
- Date published
- 12/2017
- Academic Unit
- Health Management and Policy; Biostatistics; Anesthesia
- Record Identifier
- 9983806270302771
Metrics
17 Record Views