Section 675.APPENDIX A   Calculation of Effect Size

A multiple regression approach will be employed, in which, for each provider, SES students' predicted assessment scores on the applicable State assessment required under Section 2-3.64a-5 of the School Code [105 ILCS 5/2-3.64a-5] for their grade level in the tutored subjects, based on student demographic variables and prior achievement on the applicable assessment, are compared to their obtained scores.  The difference will be expressed in the form of a "residual" score that, if positive, indicates a higher performance than expected (i.e., a positive effect), and, if negative, indicates a lower performance (a negative effect).  An effect size will then be computed by grade level within each school district to determine by how many standard deviations (based on properties of the distribution) the residual differs from zero and then aggregated across grade levels for determining the effect size used in the evaluation described in Appendix B.

(Source:  Amended at 40 Ill. Reg. 3099, effective January 27, 2016)