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Table 5 Reliability of two methods using Kappa statistics for observations reported by both methods (3897 observations in 186 children)

From: Comparison of fieldworker interview and a pictorial diary method for recording morbidity of infants in semi-urban slums

Variable P0 Pe PI BI Kappa BAK PABAK
Diarrhoea 0.962 0.940 −0.938 0.004 0.360 0.364 0.924
Fever 0.896 0.853 −0.841 0.040 0.290 0.291 0.792
Cough/cold 0.674 0.504 −0.253 0.237 0.342 0.302 0.347
Healthy 0.674 0.490 0.164 −0.219 0.361 0.329 0.347
  1. Po –Proportion observed.
  2. Pe-Proportion expected.
  3. PI = Prevalence index (difference in the probability of agreement cells (a-d)/N).
  4. BI = Bias index (difference in proportion of disagreement cells (b-c)/N).
  5. BAK is Bias-adjusted kappa. It is calculated by substituting the average values of the discordant cells instead of their original values in the regular kappa estimation formula. K = (Po- Pe)/ (1-Pe).
  6. PABAK = Prevalence-adjusted bias-adjusted kappa = 2*(Po)-1.