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Table 2 Calculation of post-test probability using likelihood ratios

From: Conceptualization of category-oriented likelihood ratio: a useful tool for clinical diagnostic reasoning

1. Odds = p r o b a b i l i t y 1 - p r o b a b i l i t y
2. Post-test odds = pre-test odds × likelihood ratios
  For example, according to table 1, post-test probability of uncomplicated UTI in case1 can be calculated as:
  Pre-test odds = 0 . 12 ( 1 - 0 . 12 ) =0.13
  Post-test odds = 0.13 × 1.5 × 1.8 × 3.1 × 4 = 4.35
  Post-test probability = 4 . 35 ( 1 + 4 . 35 ) =81%