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. 2008 Jul 8;5:7. doi: 10.1186/1742-7622-5-7

Table 1.

Expected change in precision for 67 × 3, 33 × 6 and 30 × 7 designs compared with 30 × 30 design


30 × 30
design
Observed
DEFF		 Rho 67 × 3 design 33 × 6 design 30 × 7 design
Expected
DEFF
Change
in the
width of the
CI,1
%		 Expected
DEFF
Change
in the
width of
the CI,1
%		 Expected
DEFF
Change
in the
width of
the CI,1
%
1 0 1 +111.6 1 +113.2 1 +107.0
1.25 0.0086 1.0172 +90.9 1.0431 +94.7 1.0517 +89.9
1.5 0.01724 1.0345 +75.7 1.0862 +81.4 1.1034 +77.6
2 0.03448 1.0690 +54.7 1.1724 +63.2 1.2069 +60.8
2.5 0.05172 1.1034 +40.6 1.2586 +51.3 1.3103 +49.9
3 0.06897 1.1379 +30.3 1.3448 +42.7 1.4138 +42.1
4 0.10345 1.2069 +16.2 1.5172 +31.3 1.6207 +31.8
5 0.13793 1.2759 +6.9 1.6897 +23.9 1.8276 +25.2
7 0.20690 1.4138 -4.9 2.0345 +14.9 2.2414 +17.1
10 0.31034 1.6207 -14.8 2.5517 +7.7 2.8621 +10.8

1 Relative expected change in the width of the 95% confidence interval compared to the 30 × 30 design