Selection Bias Calculator

Quantify selection bias using selection probabilities

Based on episensr R package

Input Parameters

Enter selection probabilities for each exposure-outcome group

Observed Odds Ratio

Selection Probabilities

P(S | Exposed, Case)

P(S | Unexposed, Case)

P(S | Exposed, Control)

P(S | Unexposed, Control)

Enter parameters and click calculate to see results

Formula

SBF = (S₁₁ × S₀₀) / (S₁₀ × S₀₁)

Adjusted OR = Observed OR / SBF

S represents selection probability for each exposure-outcome combination.

Selection bias occurs when the relationship between exposure and outcome differs between those selected into a study and the target population.