The Auburn, Maine, school district conducted an early literacy experiment in the fall of 2011. In September, half of the kindergarten classes were randomly assigned iPads (the intervention group) while the other half of the classes got them in December (the control group.) Kids were tested in September and December and the study measures the average difference in score gains between the control and intervention group. The experimenters tested whether the mean score for the intervention group was higher on the HRSIW subtest (Hearing and Recording Sounds in Words) than the mean score for the control group.

(a) State the null and alternative hypotheses of the test and define any relevant parameters.

(b) The p-value for the test is 0.02. State the conclusion of the test in context. Are the results statistically significant at the 5% level?

(c) The effect size was about two points, which means the mean score for the intervention group was approximately two points higher than the mean score for the control group on this subtest. A school board member argues, ‘‘While these results might be statistically significant, they may not be practically significant.” What does she mean by this in this context?