Post-traumatic stress disorder associated with life-threatening motor vehicle collisions in the WHO World Mental Health Surveys

Table 4 Sensitivity and positive predictive value of a dichotomous classification distinguishing the 5 % of respondents with highest predicted probabilities of PTSD from other respondents based on replicated 10-fold cross-validation of the final model with 20 replications^a

^aTen-fold cross-validation involves dividing the sample into 10 separate random subsamples of equal size, estimating the model in each of the 10 separate 90 % subsamples created by deleting 1 of the 10 subsamples, and applying predicted values based on each set of coefficients only to the remaining 10 % of the sample. Replicated cross-validation involves repeating the cross-validation process some number of times (20 times in the current application), with a different random split of the sample into 10 equal-sized subsamples each time. Sensitivity and positive predictive value were calculated separately in each of these 200 subsamples and averaged to produce the results reported here
^bSensitivity = Proportion of all PTSD found among the 5 % of respondent with highest predicted probabilities based on the final model
^cPositive Predictive Value = Prevalence of PTSD among respondents in the row who are among the 5 % in the total sample with the highest predicted probabilities based on the final model

ISSN: 1471-244X