From: Design effect in multicenter studies: gain or loss of power?
Group distribution among centers | Quite homogeneous | Heterogeneous | Cluster design | ||||||
---|---|---|---|---|---|---|---|---|---|
Group size per center | m 1j | m 2j | %* | m 1j | m 2j | %* | m 1j | m 2j | %* |
Center 1 (n = 57) | 16 | 41 | 28 | 11 | 46 | 19 | 0 | 57 | 0 |
Center 2 (n = 38) | 10 | 28 | 26 | 24 | 14 | 63 | 38 | 0 | 100 |
Center 3 (n = 44) | 11 | 33 | 25 | 7 | 37 | 16 | 0 | 44 | 0 |
Center 4 (n = 15) | 3 | 12 | 20 | 1 | 14 | 7 | 0 | 15 | 0 |
Center 5 (n = 41) | 9 | 32 | 22 | 8 | 33 | 20 | 0 | 41 | 0 |
Center 6 (n = 19) | 5 | 14 | 26 | 10 | 9 | 53 | 19 | 0 | 100 |
Center 7 (n = 37) | 8 | 29 | 22 | 9 | 28 | 24 | 0 | 37 | 0 |
Center 8 (n = 52) | 12 | 40 | 23 | 4 | 48 | 8 | 0 | 52 | 0 |
Center 9 (n = 12) | 3 | 9 | 25 | 1 | 11 | 8 | 0 | 12 | 0 |
Center 10 (n = 28) | 8 | 20 | 29 | 10 | 18 | 36 | 28 | 0 | 100 |
S | 0.14 | 5.79 | 33.77 | ||||||
Deff ( ρ = 0.10) | 0.91 | 1.48 | 4.28 |