Question

A psychologist is interested in the effects of animal therapy on kids who have an anxiety disorder. She knows that the population mean on a test of anxiety for these kids is 24.7 with a standard deviation of 3.9. She collects a sample of 27 children and exposes them to therapy dogs for a period of 6 months. She then tests their anxiety levels and obtains a mean of 22.3.

A. Test the hypothesis that therapy influences anxiety in children with an anxiety disorder. Use an alpha level of .05 (two-tails): State the hypotheses. Draw distribution/rejection region(s)/critical value(s). State the test statistic and state decision and communicate results.

B. Compute a 95% confidence interval for the mean anxiety of kids who undergo animal therapy.

C. Compute the effect size and interpret it using Cohen’s guidelines.

Answer 1

given data are:-

sample mean () = 22.3

sample size (n) = 27

population sd () = 3.9

a).hypothesis:-

test statistic be:-

z critical value for alpha=0.05, both tailed test be:-

rejection region:-

decision:-

.....so, we reject the null hypothesis.

conclusion:-

there is sufficient evidence to claim that therapy influences anxiety in children with an anxiety disorder at 0.05 level of significance.

b).the 95% confidence interval for the mean anxiety of kids who undergo animal therapy is:-

c)the effect size is:-

interpretation:-

the difference between mean anxiety level in kids before and after exposing them to therapy dogs for a period of 6 months is relatively medium (0.6 standard deviations)

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