Trials which randomize practices II: sample size.
Fam Pract
; 15(1): 84-7, 1998 Feb.
Article
em En
| MEDLINE
| ID: mdl-9527303
ABSTRACT
BACKGROUND:
When practices are randomized in a trial and observations are made on the patients to assess the relative effectiveness of the different interventions, sample size calculations need to estimate the number of practices required, not just the total number of patients.OBJECTIVE:
Our aims were to introduce the methodology for appropriate sample size calculation and discuss the implications for power.METHOD:
A worked example from general practice is used.DISCUSSION:
Designs which randomize practices are less powerful than designs which randomize patients to intervention groups, particularly where a large number of patients is recruited from each practice. Studies which randomize few practices should be avoided if possible, as the loss of power is considerable and simple randomization may not ensure comparability of intervention groups.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ensaios Clínicos Controlados Aleatórios como Assunto
/
Estatística como Assunto
/
Tamanho da Amostra
/
Medicina de Família e Comunidade
Tipo de estudo:
Clinical_trials
Limite:
Humans
Idioma:
En
Revista:
Fam Pract
Ano de publicação:
1998
Tipo de documento:
Article
País de afiliação:
Reino Unido