Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 2 34 Effects MPH on Academic Performance Table 2.1 provides an overview of all meta-analytic results, heterogeneity statistics and the results of the publication bias analyses. Math The meta-analytic results showed that MPH significantly improved math accuracy by 3.0% ( p =.001) and math productivity by 7.8% ( p <.001), see Figure 2.2 and Figure 2.3, respectively. Results from the four studies not qualifying for meta-analysis and reviewed in our qualitative synthesis (see Table E2.1) corroborate our meta-analytic findings. Reading For reading, meta-analytic results showed that improvements in accuracy with MPH were not significant (improved by 6.2%, p=.089), see Figure 2.4. In contrast, MPH increased the number of reading items attempted ( d =.47, p <.001), see Figure 2.5. Spelling The results from our qualitative synthesis were inconclusive with only one out of three studies reporting significant improvements in spelling with MPH compared to placebo, see Table E2.1. All effect sizes reflecting the effects of MPH on math and reading performance showed low heterogeneity, see Table 2.1. Table 2.1 Meta-analytic results for the effects of MPH on academic performance Meta-analytic effect size Heterogeneity Publication bias k ES 95% CI P I 2 ,% Q(df) P Fs N P (EF) 95% CI (EF) P ( N ) P(RB) Math accuracy 29 .030 .012, .048 .001 0 9.601(28) 1.00 59 .04 .0036, 1.0021 .97 .29 Math productivity 17 .078 .043, .112 < .001 0 2.855(16) 1.00 66 .20 -.2130, .9525 .91 .44 Reading accuracy 9 .062 -.009, .134 .089 0 1.389(8) .994 0 .35 -.7168, 1.7524 .77 .99 Reading attempted 5 .470 .302, .637 <.001 0 0.597(4) .963 34 .16 -.7057, 2.6173 .73 .79 Note. MPH, methylphenidate; k , number of studies; ES, effect size (risk difference for math accuracy, math productivity and reading accuracy, Cohen’s d for reading attempted); CI, confidence interval; Fs N , fail-safe n; P (EF), P value of Egger funnel plot asymmetry; P ( N ), P value of the relation between sample size and effect size, P(RB), P value of the relation between risk of bias and effect size.