PT  - JOURNAL ARTICLE
AU  - M Underwood
AU  - A Barnett
AU  - S Hajioff
TI  - Cluster randomization: a trap for the unwary.
DP  - 1998 Mar 01
TA  - British Journal of General Practice
PG  - 1089--1090
VI  - 48
IP  - 428
4099  - http://bjgp.org/content/48/428/1089.short
4100  - http://bjgp.org/content/48/428/1089.full
SO  - Br J Gen Pract1998 Mar 01; 48
AB  - Controlled trials that randomize by practice can provide robust evidence to inform patient care. However, compared with randomizing by each individual patient, this approach may have substantial implications for sample size calculations and the interpretation of results. An increased awareness of these effects will improve the quality of research based on randomization by practice.