Question

A school psychologist believes that a popular new hypnosis technique increases depression. The psychologist collects a sample of 25 students and gives them the hypnosis once a week for two months. Afterwards the students fill out a depression inventory in which their average score was 53.88. Normal individuals in the population have a depression inventory average of 50 with a variance of 100.00. What can the psychologist conclude with α = 0.01?

a) What is the appropriate test statistic?
---Select--- na ,z-test ,One-Sample t-test ,Independent-Samples t-test ,Related-Samples t-test

b)
Population:
---Select--- students receiving hypnosis ,normal individuals, two months ,new hypnosis ,technique depression
Sample:
---Select--- students receiving hypnosis ,normal individuals ,two months, new hypnosis ,technique depression

c) Compute the appropriate test statistic(s) to make a decision about H₀.
(Hint: Make sure to write down the null and alternative hypotheses to help solve the problem.)
critical value = ; test statistic =  
Decision: ---Select--- Reject H0 or Fail to reject H0

d) If appropriate, compute the CI. If not appropriate, input "na" for both spaces below.
[ , ]

e) Compute the corresponding effect size(s) and indicate magnitude(s).
If not appropriate, input and select "na" below.
d =   ;   ---Select--- na trivial effect small effect medium effect large effect
r² = ;   ---Select--- na trivial effect small effect medium effect large effect

f) Make an interpretation based on the results.

A.The depression of students that underwent hypnosis is significantly higher than the population.

B.The depression of students that underwent hypnosis is significantly lower than the population.    

C.The depression of students that underwent hypnosis is not significantly different than the population.

Answer 1

a)

z-test

b)

Population:
normal individuals

Sample:
students receiving hypnosis

c)

d)

Here test is right tailed so we need one sided confidence interval. Following is the 98% confidence interval:

The required confidence interval is (49.23, infinity).

e)

The cohen's d effect size:

It is medium effect size.

---------------

r^2 = na

f)

C.The depression of students that underwent hypnosis is not significantly different than the population.