| NOTES: The follow-up GRADE assessment was administered in the spring of 2007 near the end of students’ ninth-grade year. The estimated impacts are regression-adjusted using ordinary least squares, controlling for blocking of random assignment by school and for random differences between the ERO and non-ERO groups in their baseline reading comprehension test scores and age at random assignment. The values in the column labeled “ERO Group” are the observed means for students randomly assigned to the ERO group. The “Non-ERO Group” values in the next column are the regression-adjusted means for students randomly assigned to the non-ERO group, using the observed mean covariate values for the ERO group as the basis for the adjustment. The national average for standard score values is 100, and its standard deviation is 15. The grade equivalent and percentile are those associated with the average standard score as indicated in the GRADE Teacher's Scoring and Interpretive Manual (Level H, Grade 9, Spring Testing, Form B). No statistical tests or arithmetic operations were performed on these reference points. The estimated impact effect size is calculated as a proportion of the standard deviation of the non-ERO group average (reading comprehension = 10.035; reading vocabulary = 9.827). A two-tailed t-test was applied to the impact estimate. The statistical significance is indicated (*) when the p-value is less than or equal to 5 percent. Rounding may cause slight discrepancies in calculating sums and differences. |
