A school psychologist is interested in determining if children with attention deficit disorder (ADD) learn better if English literature is read to them rather than having them read the material themselves. A random sample of 10 sixth graders with ADD is selected and divided into two groups of 5 each. One of the groups has a story read to them (Listening Group) and the other reads the story themselves (Reading Group). A quiz on the story is given after each group has finished reading or hearing the story. The following scores were obtained with 20 being a perfect score. Assume there is a real effect. The size of the effect, using equals _________.
A) 1.72
B) 0.58
C) 0.32
D) 1.65

Question

A school psychologist is interested in determining if children with attention deficit disorder (ADD) learn better if English literature is read to them rather than having them read the material themselves. A random sample of 10 sixth graders with ADD is selected and divided into two groups of 5 each. One of the groups has a story read to them (Listening Group) and the other reads the story themselves (Reading Group). A quiz on the story is given after each group has finished reading or hearing the story. The following scores were obtained with 20 being a perfect score.  Assume there is a real effect. The size of the effect, using equals _________.
A) 1.72 
B) 0.58 
C) 0.32 
D) 1.65

Quizplus · Accepted Answer

The effect size can be calculated using Cohen's d formula, which is (mean of group 1 - mean of group 2)/pooled standard deviation. The mean score for the reading group is 11.4 and for the listening group is 15.8. The pooled standard deviation is 4.03. Plugging in the values, we get a Cohen's d of 1.65. This indicates a large effect size. Therefore, choice D is the best answer.

A School Psychologist Is Interested in Determining If Children with Attention