Question

 

An investigator conducts a study to examine the benefits of psychotherapy for individuals with depression. Specifically, the investigator predicts that depressed individuals who receive psychotherapy in addition to drug therapy for depression will display significantly lower levels of depression than persons with a diagnosis of depression who receive only drug therapy. The investigator assigns 10 subjects to each of the two conditions stated above. After three months the investigator measures depression using a scale in which higher scores reflect higher levels of depression.

1. Write the null and alternative hypotheses for testing the investigator’s prediction.

2. Please use SPSS to test the null hypothesis stated above and attach the SPSS output herewith.

3. Please provide a sentence in APA format for a results section that states the conclusion the investigator is entitled to draw. You can type the sentence at the SPSS output. Note : Your typed responses in a colored font will help me find your responses faster.Please attach a word doc. file as your attachment.

Psychotherapy plus drug therapy group: 23, 19, 16, 18, 15, 22, 16, 18, 19, 20

Drug therapy only: 24, 27, 26, 28, 29, 24, 26, 25, 22, 28

 

Answer 1

Answer:

Given drug therpy is 24, 27, 26, 28, 29, 24, 26, 25, 22, 28

but null and hypotheses for testing are as follows

1) Drug therapy only: 24, 27, 26, 28, 29, 24, 26, 25, 22, 28, 23, 24

while your problem stated "The investigator assigns 10 subjects to each of the two conditions stated above" so I will take first 10 observations of 2nd group

Drug therapy only: 24, 27, 26, 28, 29, 24, 26, 25, 22, 28

2) Here researcher want to test ,whether psychotherapy benefits for individuals with depression. And,since higher scores reflect higher levels of depression so if psychotherapy benefits for individuals with depression then mean score of Psychotherapy plus drug therapy group must be less than Drug therapy only group. Let sample 1 shows Psychotherapy plus drug therapy group and sample 2 shows Drug therapy only group. Hypotheses are;

Here we have 2 independent samples so independent sample t test will be used. Following is the output of the excel generated by excel:

Here test is 1-tailed so p-value of the test is 0.000015.

Since p-value is less than 0.05 so we reject the null hypothesis. That is we can conclude that  psychotherapy benefits for individuals with depression.

3) next we have APA format result are shown below

APA format

t(17) = -6.814, p < 0.05