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Result of a hand search for cluster randomised trials in the British Medical Journal
| Year | Vol | Trials | Clustering ignored | Ignoring clustering judged as important | Found in Web of Science search |
| 2003 | 326-7 | 9 | 0 | 0 | 5 |
| 1998 | 316-7 | 4 | 1(?) | 1 | 0 |
| 1993 | 306-7 | 4 | 3 | 2 | 0 |
| 1988 | 296-7 | 0 | 0 | 0 | 0 |
| 1983 | 286-7 | 1 | 1 | 1 | 0 |
? doubtful whether clustering taken into account
