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Table 5 Information for estimating PPV for those scoring 9 or more in the 2001 population survey

From: Development of a questionnaire weighted scoring system to target diagnostic examinations for asthma in adults: a modelling study

Stratum (i) (number of 'yes' answers to key questions) Score (j) Number of respondents ω ij proportion of population postal questionnaires in stratum i, ∏' ij prevalence of asthma for score j in stratum i ω ij × ∏' ij
6 12 2 0.0250 0.9914 0.0248
6 11 6 0.0750 0.9914 0.0744
6 10 5 0.0625 0.9867 0.0616
6 9 7 0.0875 0.7996 0.0700
5 12 1 0.0125 0.7181 0.0090
5 11 3 0.0375 0.7181 0.0269
5 10 9 0.1125 0.9777 0.1100
5 9 16 0.2000 0.8938 0.1788
4 10 3 0.0375 0.8908 0.0334
4 9 11 0.1375 0.9975 0.1371
1 – 3 11 1 0.0125 0.9633 0.0120
1 – 3 10 3 0.0375 0.9757 0.0366
1 – 3 9 13 0.1625 0.9880 0.1606
Total   80 1   
  1. Estimated PPV for those scoring 9 or more: