Overlap between treatment and control distributions as an effect size measure in experiments.
Psychol Methods
; 21(1): 61-8, 2016 Mar.
Article
em En
| MEDLINE
| ID: mdl-26523436
ABSTRACT
The proportion π of treatment group observations that exceed the control group mean has been proposed as an effect size measure for experiments that randomly assign independent units into 2 groups. We give the exact distribution of a simple estimator of π based on the standardized mean difference and use it to study the small sample bias of this estimator. We also give the minimum variance unbiased estimator of π under 2 models, one in which the variance of the mean difference is known and one in which the variance is unknown. We show how to use the relation between the standardized mean difference and the overlap measure to compute confidence intervals for π and show that these results can be used to obtain unbiased estimators, large sample variances, and confidence intervals for 3 related effect size measures based on the overlap. Finally, we show how the effect size π can be used in a meta-analysis.
Texto completo:
1
Eixos temáticos:
Pesquisa_clinica
Base de dados:
MEDLINE
Assunto principal:
Projetos de Pesquisa
/
Metanálise como Assunto
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Interpretação Estatística de Dados
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Modelos Estatísticos
Tipo de estudo:
Prognostic_studies
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Risk_factors_studies
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Systematic_reviews
Limite:
Humans
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article