A META-ANALYSIS OF SCHOOL MOBILITY EFFECTS ON READING AND MATH ACHIEVEMENT IN THE ELEMENTARY GRADES

Majida A.A. MEHANA

American children have one of the highest residential mobility rates when compared to several Western countries and Japan. In the U.S., an estimated six million elementary school‑aged children change schools every year. This study evaluated the effects of school mobility on reading and math achievement in the elernentary grades (k‑6) using meta­analysis for studies dated between 1975 and 1994. Mobility was defined as any change in schools.

The sample sizes of the 26 studies examined ranged from 62 to 15,000. The statistics in the studies were converted into d which is an effect size (ES) derived by taking the mean difference between the treatment and control groups and dividing by the pooled standard deviation. The individual effect sizes were almost all negative except in cases where the sample consisted of military personnel's dependents.

           A composite effect size was computed and for homogeneity. The composite effect size for reading, d was significant but the individual effect sizes were heterogeneous implyying inconsistencies in the direction of the relationship between readine and mobility. To avoid discarding any studies the sample sizes of the two largest effect sizes were substituted for 1995. The composite effect size remained approximately ‑.25 and corresponded to a z of.40. The reading score of the average individual in the mobile group exceeded that of only 40 percent in the non‑mobile group.

         Similarly, the results were heterogeneous for math achievement. Math effect sizes ‑.24 and ‑.22 before and after replacement of the two largest sample sizes by 1995 corresponded to a z of.41. The math score of the average individual in the mobile group exceeded that of only 41 percent in the non‑mobile group. Regression models indicated that frequently mobile children with low SES and enrolled in earlier grades had lower math effect sizes than the other groups.

          Using the binomial effect display method as an alternative method to interpret the effect sizes, I found that mobility was associated with a reduction in achievement from 56% to 44% for both reading and math.

In conclusion, mobility was negatively associated with reading and math achievement. The effects were relatively small to moderate in magnitude depending on the frequency of mobility. The mean effect sizes for mobile groups were negative with the frequently mobile group more impacted than the less frequently mobile or non‑mobile groups.