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Study group characteristics
| Group | Observation hours | Mean group size | Subjects 3+ yrs | Group formation |
|---|---|---|---|---|
| 1 | 182.1 | 176.5 | 92 | 2003 |
| 5 | 251.8 | 137.1 | 85 | 1986 |
| 8 | 231.8 | 160.1 | 96 | 1991 |
| 10 | 178.1 | 164.4 | 76 | 1976 |
| 14 | 226.3 | 108.3 | 57 | 2003 |
| 16 | 163.9 | 150.3 | 74 | 2004 |
| 18 | 175.5 | 197.9 | 97 | 2001 |
