© 2025 Vista Higher Learning Vista’s Bridges: A Study of Reading Growth in MLs 11 Table 2 Student Demographics for All Participants Before Matching Characteristic Control N Treatment N Total Sex Boys 296 166 462 Girls 234 139 373 Total 530 305 835 Race White 502 287 789 Non-White 28 18 46 Total 530 305 835 Free Lunch Eligibility Not Eligible 246 146 392 Eligible 284 159 443 Total 530 305 835 The demographic profile shows that both groups were comparable overall. Although most students identified as White, the study included a smaller group of racially diverse students representative of the district population. How We Created Comparable Student Groups Given that random sampling is often not possible (as was the case for this study), an alternative is to create matched groups. For everyone from the treatment group pool, an individual from the control group pool who is similar in ability and background is selected. We created matched treatment and control groups using Propensity Score Matching (PSM), a statistical technique that permits matching based on several variables. We examined the statistical relationship between study group membership on the one hand, and initial reading ability (iReady Reading assessment pretest scores), sex, race, and free or reduced-cost lunch eligibility on the other (using logistic regression). We combined the results across the set of test scores and background characteristics in relationship to study group membership into a single number, a propensity score. These PSM scores could then be used to balance, or match, the two study groups based on the characteristics mentioned. For everyone from the treatment group pool, an individual from the control group pool who was similar in ability and background was selected. This was done until a match was found for each treatment group pool member (or until we found that there was no match for a treatment group pool member). To be considered a match, the propensity scores for the two students in the potential matched pair were required to be within 2% of each other. The matched group of students became the final matched treatment and control group sample for the study. There were a total
RkJQdWJsaXNoZXIy MjUyNzA0NQ==