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Training model based on the first 32 quarters of enrollment |
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| All ACTG studies |
Excluding substudies |
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| Parameters |
Effect (95% CI) |
Effect (95% CI) |
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| AR1 |
0.04 (-0.37, 0.46) |
-0.09 (-0.51, 0.33) |
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| Time trend effect |
29.7 (18.9, 40.5) ‡ |
12.8 (3.9, 21.7) § |
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| (per quarter) |
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| Large studies effect *(per point weight) |
699.7 (535.5, 864.0) ‡ |
420.3 (284.2, 556.4) ‡ |
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| Early starting effect † |
-83.3 (-427.3, 260.7) |
-436.7 (-731.1,-142.2) § |
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| Studies starting in same quarter (per study) |
20.6 (-1.4, 42.5) |
-1.0 (-23.5, 21.4) |
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| Seasonal effect |
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| Spring |
152.7 (-78.8, 406.2) |
189.3 (-32.4, 410.9) |
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| Summer |
185.3 (-43.2, 413.7) |
115.3 (-90.6, 321.2) |
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| Fall |
-144.5 (-365.2, 76.2) |
-96.7 (-308.8, 115.4) |
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| Constant |
137.5 (-152.2, 427.2) |
576.5 (309.3, 843.7) ‡ |
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ACTG: AIDS Clinical Trials Group, AR1: First-order autoregressive parameter * Sum of weights for large studies in each quarter: ½ for a large study which is initiated in that quarter, 1 for a large study which is on its second quarter of enrollment, and ½ for a large study which is on its third quarter of enrollment. † Dummy variable for first 3 quarters (Fall 1986-Spring 1987) ‡ p < 0.001 §0.001 ≤ p < 0.05 | |||
Haidich and Ioannidis BMC Medical Research Methodology 2001 1:4 doi:10.1186/1471-2288-1-4 |
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