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Table 2 Trends in discrepancies, PTSD data, fitness status and health outcomes by response wave (number of times a person was contacted before response)

From: How many mailouts? Could attempts to increase the response rate in the Iraq war cohort study be counterproductive?

Number of contacts 1 2 3 4+ All p-value
Full responders (N) 7,384 1,651 758 441 10,234  
Indicators for misclassification       
Discrepant 1 (%) 11.8 11.1 13.1 12.3 11.8 0.5
Discrepant 2 (%) 12.8 12.9 15.8 16.3 13.2 0.007
At least 1 health question missing (%) 2.4 4.0 5.6 7.3 3.1 <0.001
Indicators for outcome prevalence       
Unfit (%) 22.8 21.8 22.3 21.7 22.4 0.4
PTSD 50+ (%) 3.7 4.7 4.1 3.3 3.9 0.6
Symptoms 18+ (%) 10.8 11.7 11.1 9.8 10.9 0.97
  1. Estimates are weighted to allow for oversampling of reservists. p-values are for trend
  2. Those with missing values to either question are excluded from discrepant 1, but included as discrepancies in discrepant 2