Method | Brief description |

Adjust for Selection Bias [9] [12] | Include the variable associated with selection in the analysis, to reduce selection bias in a similar way to confounding [13] . |

Bias Breaking [5] | A method which produces bias-adjusted estimates for the odds ratios in case control studies. |

Imputation [8] | Often multiple imputation; replace missing values with reasonable estimates using the collected data. |

Population Data [7] | Use population data in place of control data in a case control study. |

Post-Stratification [14] | Classify unmatched samples of cases and controls based on their values on one or more of the variables in the study. Similar to stratified sampling or frequency matching. |

Predict the Bias [15] - [17] | Use information from non-participants to try to predict the amount of bias present. |

Propensity Score [10] | Can be used to match cases and controls, or as an additional covariate during analysis. |

Sensitivity Analysis [6] [12] | A method for estimating the direction and magnitude of the bias. |

Stratification [11] | Calculate estimates conditional on at least one other variable, which can lead to unbiased estimates within strata. |

Weighting [4] | Usually inverse probability weighting; use external data to assign each subject a weight which is the inverse of their probability of selection, to allow them to represent non-participants. |