The actual formulas original proposed for ** d** are quite different than the ones below. These are what many call

*computational formulas*—the logic of why they work is not readily apparent. They have the advantage of being easy to compute and easy to enter into a spreadsheet, which is why we will use them rather than the more informative

*heuristic formulas*.

r = sqrt( ( t^{2} ) / ( ( t^{2} ) + ( df * 1) ) )

d = (t*2) / (sqrt(df) )

Where:

** r** = Effect Size

** d** = Cohen’s

*d*Value (Standardized Mean Difference)

** t **= t-Test Value

** df** = Degrees of Freedom.

In Excel, **SQRT** is the square root function. For t-squared, just substitute the cell that you are using to enter ** t** multiplied by itself. The

**in the formula must be swapped out for the cell containing the**

*df***value. Here is an example of how this might look in Excel:**

*df*Last Modified: 06/04/2021