## PSYC 354 Homework 8

Part I: Questions 1a-1g

Fill in the highlighted blanks with the best word or words.

1-a)

You use a t-test when you know the population ________ but not the population ________.

1-b)

The t-statistic indicates the distance of a sample mean from the ________ in terms of estimated standard error units.

1-c)

The 2 groups compared in the single-sample t-test are the sample and the ________.

1-d)

The number of scores that are free to vary when you are estimating a population parameter from a sample is called the ________.

1-e)

A researcher reports the results of a single-sample t-test as t(46) = 2.37. The degrees of freedom for this t-test are ______, which means there were ____ total participants in the researcher’s sample.

1-f)

Based on the t tables, the critical values of the t-statistic for a two-tailed test with df = 11 and a p level of 0.05 are ________.

1-g)

When your t-statistic in your results exceeds your critical cutoffs, you ________ the null hypothesis.

Part I: Question 2-3

End-of-chapter problems:

Complete the following exercises. If applicable, remember to show work in your homework document to receive partial credit.

2)

Explain what each part of the following statistical phrase represents, as it would be reported in APA format: t(8) = 2.98, p = .03

t

Answer

8

Answer

2.98

Answer

p

Answer

.03

Answer

3)

Calculate the critical degrees of freedom and identify the critical t value for a single-sample t test in each of the following situations:

3-a) Two-tailed test, N = 10, p = .10

df= Answer

critical t = Answer

3-b) Two-tailed test, N = 36, p = .05

df= Answer

critical t = Answer

3-c) One-tailed test, N = 81, p = .01

df= Answer

critical t = Answer

Part II: SPSS Analysis

Module/Week 8 Exercise File 1

Open the “Module/Week 8 Exercise File 1” document (found in the course’s Assignment Instructions folder) in order to complete these exercises.

Part II:

Exercises 1-3

Use file: Module/Week 8 Exercise File 1

• The anger scores for 6 fictional Marines following a month-long exercise are entered in the Module/Week 8 Exercise File 1 document (found in the Assignment Instructions folder).

• Using these data, run 3 single-sample t-tests to compare the Marines’ mean anger score to the following population values:

Population mean anger scores

Population of college men: = 8.1

Population of adult men: = 9.5

Population of male psychiatric outpatients: = 12

• For each test, paste the output and write a Results section in current APA style

o As demonstrated in the presentation and in the textbooks.

• There will be 3 sets of output and 3 results sections using this data set

o 1 for each test involving a different population mean.

1-a)

Population of college men: = 8.1.

Answer: SPSS output of the t-Test

1-b)

Write a results section in current APA style describing the outcome.

All homework results sections must follow the example given in the SPSS presentation. Results sections are paragraphs and must include the APA-formatted statistical statement.

Answer

2-a)

Population of adult men: = 9.5

Answer: SPSS output of the t-Test

2-b)

Write a results section in current APA style describing the outcome. See (1b) for details.

Answer

3-a)

Population of male psychiatric outpatients: = 12

Answer: SPSS output of the t-Test

3-b)

Write a results section in current APA style describing the outcome. See (1b) for details.

Answer

Part III: SPSS Data Entry and Analysis

Data provided below.

Attitudes Toward

Technology Scale Scores

12

25

8

12

10

11

7

7

13

5

8

7

9

12

19

Part III:

Questions 1-2

Do elderly people have less positive attitudes toward technology than people in general?

A social psychologist assessed the attitudes of 15 elderly people using a scale where a lower score indicates a less positive attitude overall. The mean on this scale for the general population is 16.8. The data for the participants are shown in the table below.

Using SPSS, conduct a single-sample t-test to answer the social psychologist’s research question.

1-a)

Paste appropriate tabular output here

Answer: SPSS output of the t-Test

1-b)

Paste appropriate SPSS graph here

Answer: SPSS graph

2-a)

Write a results section in current APA style describing the outcome. Refer to earlier directions for details of what is expected.

Answer:

Part IV: Cumulative

Data provided below for respective questions.

Part IV: Question 1a & 1b (Non-SPSS)

• Age at onset of dementia was determined in the general population to be = 69.8 and = 2.8.

• Use this information to answer the following:

1-a)

Based on the data you have and the z table, what percentage of people might start to show signs of dementia at or before age 65?

Answer

Work:

1-b)

What two ages correspond to +/-1 z-score from the mean (i.e. a z score of 1 and -1)?

Answer (+1 z)

Work:

Answer (-1 z)

Work:

Part IV: Question 2a-2b (Non-SPSS)

For each of the following scenarios, compute the effect size and state whether it is approximately small, medium, or large.

2-a)

Participants in an inpatient study of treatment for OCD complete an anxious feelings inventory which is then compared to the general population.

The sample mean is M = 25.

The mean in the general population of inpatients on this inventory is = 35.1,

and the population standard deviation is = 1.7.

Effect Size:

Answer

Work:

Small/Med/Large:

Answer

2-b)

A mood assessment in a sample of 15 gym members has a mean of M = 81.

The mean in the general population on this measure is = 77.5 with a standard deviation of = 5.3.

Effect Size:

Answer

Work:

Small/Med/Large:

Answer