Conversion | Justification |

IRR to RR
| The following formula, straightforwardly derived from the definitions of incidence rate ratio (IRR) and risk ratio (RR), converts the former into the latter: Fortunately, if the incidences are small enough, the average follow-up times are similar in exposed and non-exposed, the fraction in the left is approximately 1 and thus: |

RD to RR
| The following formula, straightforwardly derived from the definitions of risk difference (RD) and RR, converts the former into the latter: Thus, analysts might need an estimation of the probability of developing the disease ( p) in the non-exposed. |

RR to OR
| The following formula, straightforwardly derived from the definitions of RR and OR, converts the former into the latter: Fortunately, if the probabilities of developing the disease ( p) are small enough, the fraction in the left is approximately 1, and thus: |

RoM to MD | The following formula, straightforwardly derived from the definitions of ratio of means (RoM) and mean difference (MD), converts the former into the latter: Thus, analysts might need an estimation of the mean ( m) in controls. |

MD to Glass'Δ | The following formula, straightforwardly derived from the definitions of mean difference (MD) and Glass' Δ, converts the former into the latter: Thus, analysts might need an estimation of the SD ( s) in controls. |

Glass'Δ to Cohen’s d
| The following formula, straightforwardly derived from the definitions of Glass'Δ and Cohen’s d, converts the former into the latter: Fortunately, if the variances ( s
^{2}) in cases and controls are similar enough, the square root in the left is approximately 1, and thus: |

Hedge’s g to Cohen’s d
| The following formula, straightforwardly derived from the definitions of Hedge’s g and Cohen’s d, converts the former into the latter: Fortunately, if the sample sizes are large enough, the small-sample correction factor ( J) is approximately 1, the fraction in the left is approximately 1 and thus: |

Pearson’s r to Cohen’s d
| The following standard formula23 converts a Pearson’s r into an approximate Cohen’s d: |