Exemplary data set sample size calculation for Wilcoxon-Mann-Whitney tests.
Stat Med
; 29(1): 108-15, 2010 Jan 15.
Article
de En
| MEDLINE
| ID: mdl-19890884
ABSTRACT
Zhao, Rahardja and Qu consider sample size calculation for Wilcoxon-Mann-Whitney (WMW) tests for data with ties, and present a straightforward formula. We observe that the 'exemplary data set' approach, usually applied in more complex situations, has a close relationship to the Zhao-Rahardja-Qu method for WMW sample size estimation and they are asymptotically equivalent. Therefore, the exemplary data set approach can be used to easily obtain estimates similar to those that the closed formula gives. We illustrate application of both methods for a WMW sample size estimation example, and also extend the simulation study presented by Zhao et al. We find that the Zhao-Rahardja-Qu formula (and by extension the exemplary data set method) can give estimates just as accurate as those obtained using either the Kolassa approach (via nQuery Advisor) or the O'Brien-Castelloe approach (via SAS 9.2 PROC POWER), for 11 and 12 allocation ratios. However, the latter two methods can be more accurate for a ratio of 14 or 119. Finally, we note the general utility of the exemplary data set approach for sample size estimation, even in other situations where closed-form sample size formulae exist.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Modèles statistiques
/
Biométrie
/
Statistique non paramétrique
/
Taille de l'échantillon
Type d'étude:
Risk_factors_studies
Limites:
Humans
Langue:
En
Journal:
Stat Med
Année:
2010
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique