# Single-sample t-test

HOMEWORK 8

Single-Sample T-Test

When submitting this file, be sure the filename includes your full name, course and section. Example: HW8_JohnDoe_354B01

________________________________________

Part I: Concepts

Questions 1-3

________________________________________

These questions are based on the Nolan and Heinzen reading and end-of-chapter questions.

________________________________________

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(58) = 2.50. 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 = 9 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(6) = 1.98, p = .047

t Answer

6 Answer

1.98 Answer

p Answer

.047 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 = 47, p = .05 df= Answer critical t = Answer

3-c) One-tailed test, N = 80, 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

End-of-chapter exercise 9.37 in Nolan and Heinzen text________________________________________

• End-of-chapter exercise 9.37 in Nolan and Heinzen describes a study of anger and mood in a sample of 60 Marines following a month-long intense training exercise.

• The anger scores for 6 fictional Marines 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: = 8.9

Population of adult men: = 9.2

Population of male psychiatric outpatients: = 13.5

• 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: = 8.9.

Output

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: = 9.2

Output

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: = 13.5

Output

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

11

20

7

10

13

12

5

9

14

6

5

7

9

14

12

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

Output

1-b) Paste appropriate SPSS graph here

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 for a sample of adults between the ages of 60 and 75.

• For a sample of 20 subjects, M = 69.8 and s = 2.79.

• 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) If you consider the normal range of onset in this population to be +/-1 z-score from the mean, what two ages correspond to this?

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 = 26.2.

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

and the population standard deviation is 1.5.

Effect Size: Answer Work:

Small/Med/Large: Answer

2-b) A mood assessment in a sample of 15 gym members has a mean of 83 and a standard deviation of 5.6.

The mean in the general population on this measure is 79.5.

Effect Size: Answer Work:

Small/Med/Large: Answer

Submit Homework 8 by 11:59 p.m. (ET) on Friday of Module/Week 8. Remember to name file appropriately.

Done!

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#### Solution Preview

HOMEWORK 8

Single-Sample T-Test

When submitting this file, be sure the filename includes your full name, course and section. Example: HW8_JohnDoe_354B01

________________________________________

Part I: Concepts

Questions 1-3

________________________________________

These questions are based on the Nolan and Heinzen reading and end-of-chapter questions.

________________________________________

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 _mean_ but not the population _standard deviation__.

1-b) The t-statistic indicates the distance of a sample mean from the _population mean_ in terms of estimated standard error units.

1-c) The 2 groups compared in the single-sample t-test are the sample and the _population_.

1-d) The number of scores that are free to vary when you are estimating a population parameter from a sample is called the _degress of freedom_.

1-e) A researcher reports the results of a single-sample t-test as t(58) = 2.50. The degrees of freedom for this t-test are __58_, which means there were _59__ 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 = 9 and a p level of 0.05 are _+/- 2.262_.

1-g) When your t-statistic in your results exceeds your critical cutoffs, you _reject_ 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(6) = 1.98, p = .047

t t-test

6 Degrees of freedom

1.98 The value of the t test statistic

p The p-value = .047. If p < 0.05, we reject the null hypothesis. If p > 0.05, we do not reject the null hypothesis.

.047 The p-value

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= 10-1=9 critical t = 1.833

3-b) Two-tailed test, N = 47, p = .05 df= 47-1=46 critical t = 2.013

3-c) One-tailed test, N = 80, p = .01 df= 80-1=79 critical t = 2.64

________________________________________

Part II: SPSS Analysis

Module/Week 8 Exercise File 1 ________________________________________

Open the "Module/Week 8 Exercise File 1" document (found in the ...

#### Solution Summary

The expert examines a single-sample t test.