1. ISAT Effect Size Results for Idaho English Language Arts & Mathematics Grades 3-8 and Bert Stoneberg, Ph.D. K-12 Research Idaho

2. “Practical significance” of the difference between two mean scores for an ISAT subject/grade test
Legend for this sample “Effect Size” graph for
Magnitude of the gain, i.e., practical significance of the difference between the average/mean scores
Magnitude of the loss , i.e., practical significance of the difference between the average/mean scores
Magnitude of the trend gain/loss from 2015 to The trend line is updated after each assessment (i.e., magnitudes).

3. Calculation of “Effect Size”
The effect size or the practical significance of the difference between two means or the magnitude of the difference between two means is calculated by dividing the difference between two means by their pooled standard deviations.