Enter the means and standard deviations of two groups into the calculator to determine the Hattie effect size. This calculator helps to evaluate the magnitude of the difference between two groups.
Hattie Effect Size Formula
The following formula is used to calculate the Hattie effect size (d):
d = (M1 - M2) / SDpooled
Variables:
- M1 is the mean of Group A
- M2 is the mean of Group B
- SDpooled is the pooled standard deviation of Group A and Group B
To calculate the Hattie effect size, subtract the mean of Group B from the mean of Group A and divide the result by the pooled standard deviation of the two groups.
What is Hattie Effect Size?
Hattie effect size is a measure of the strength of the relationship between two variables or the magnitude of the difference between two groups. It is commonly used in educational research to determine the impact of various influences on student achievement. The effect size is calculated using the means and standard deviations of the groups being compared. An effect size of 0.2 is considered small, 0.5 medium, and 0.8 large, according to Hattie’s benchmarks.
How to Calculate Hattie Effect Size?
The following steps outline how to calculate the Hattie Effect Size.
- First, determine the mean of Group A (M1).
- Next, determine the mean of Group B (M2).
- Then, calculate the standard deviation of Group A and Group B.
- Calculate the pooled standard deviation (SDpooled) using the formula: SDpooled = sqrt((SD1^2 + SD2^2) / 2).
- Finally, calculate the Hattie Effect Size (d) using the formula: d = (M1 – M2) / SDpooled.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Mean of Group A (M1) = 85
Mean of Group B (M2) = 78
Standard Deviation of Group A (SD1) = 9
Standard Deviation of Group B (SD2) = 10