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`d = ( M_1 - M_2 )/ sigma `

Enter a value for all fields

The **Effect Size (Cohen's d)** calculator computes the effective size based on two means and the standard deviation.

**INSTRUCTIONS**: Enter the following:

- (
**M1**) mean of population 1 - (
**M2**) mean of population 2 - (
**σ**) Standard Deviation of either or both populations

**Effect Size(θ):** The calculator returns the effective size.

The (population) effect size is based on the standardized mean difference between two populations. The formula for population effect size (Cohen's d) is:

`theta = (mu_1 - mu_2)/sigma`

where:

- θ is the effect size
- μ1 is the mean for one population
- μ2 is the mean for the other population
- σ is a standard deviation based on either or both populations

Effect Size | d |
---|---|

Very Small | 0.1 |

Small | 0.2 |

Medium | 0.50 |

Large | 0.80 |

Very Large | 1.20 |

Huge | 2.0 |

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