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A . 1. Reject H0 or 2. Fail to Reject H0? B. The size of the effect, using Cohen

ID: 3062708 • Letter: A

Question

A . 1. Reject H0 or 2. Fail to Reject H0?

B. The size of the effect, using Cohen's d equals? 1.72, 0.58, 0.32, 1.65

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. Reading Group 8 8 10 12 7 Listening Group 10 10 10 12 8 What do you conclude, using a = 0.052 tail?

Explanation / Answer

Ans:

pooled standard deviation=sqrt((1.41^2+2^2)/2)=1.732

Test statistic:

t=(10-9)/(1.732*sqrt(2/5))=0.913

df=5+5-2=8

p-value=tdist(0.913,8,1)=0.1940

As,p-value>0.05,we fail to reject H0.

B)Cohen's d Effect size=(10-9)/1.732=0.58

C)critical t value=tinv(0.05,8)=2.306

95% confidence interval

=(10-9)+/-2.306*1.732*sqrt(2/5)

=1+/-2.54

=(-1.54, -3.54)

listening reading 1 10 8 2 10 8 3 10 10 4 12 12 5 8 7 mean 10 9 std. dev 1.41 2