Quantitative Methods 2017

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FMB
Risk (probability) vs odds
a = disease, b = no disease
Risk vs odds in a common disease:
a = 50 a+b = 100
Risk = 50/100 = 0.5
Odds = 50/50 = 1
Risk vs odds in a rare disease:
a = 1 a+b = 100
Risk = 1/100 = 0.010101
Odds = 1/99 = 0.010000