# Assignment: t-Test

Using data to compare a sample to the whole population or another targeted sample of people can help researchers make predictions about future behavior or phenomena. Comparisons and predictions such as these can answer research questions and can make an argument or statement more persuasive. When there are two groups to compare, tools such as the one-sample t-test and the two-sample t-test allow researchers to make such predictions and comparisons.

This application will allow you to further practice hypothesis testing by using a t-test to compare scores from two samples in order to determine if results are statistically significant. Download the data set that you will use for this assignment from the Weekly Data Set forum found on the course navigation menu. Be sure to watch this week’s instructional video in the introduction or Learning Resources folder before beginning your Application Assignment.

**Scenario:** Imagine you are a researcher who is interested in studying whether sleep deprivation leads to increased reaction times (i.e., being slower) when driving. You randomly select a sample of 30 licensed drivers. Fifteen participants are randomly assigned to get 5 hours of sleep for three consecutive nights. The other 15 participants are randomly assigned to get 8 hours of sleep for three consecutive nights. For the purposes of this Assignment, assume that all participants sleep exactly the required amounts. After the third night, all participants take a driving simulation test that measures their reaction times.

You can find the data for this Assignment in the Weekly Data Set forum.

#### By Day 7

**To complete this Assignment, submit** a response to each of the following. Use SPSS to determine if amount of sleep is related to reaction time.

- Explain whether the researcher should use an independent-samples t-test or a related-samples t-test for this scenario. Provide a rationale for your decision.
- Identify the independent variable and dependent variable.
- Knowing the researcher believes that people who sleep less will have slower reaction times, state the null hypothesis and alternate hypothesis in words (not formulas).
- Explain whether the researcher should use a one-tailed test or two-tailed test and why.
- Identify the obtained t value for this data set using SPSS.
- State the degrees of freedom and explain how you calculated it by hand.
- Identify the p value using SPSS.
- Explain whether the researcher should retain or reject the null hypothesis. Provide a rationale for your decision. Are the results statistically significant?
- Explain what the researcher can conclude about the relationship between amount of sleep and reaction times.

Be sure to fully explain the rationale for your answer to each question, including evidence from the text and Learning Resources.

Provide an APA reference list.

Submit three documents for grading:

- Your text (Word) document with your answers and explanations to the assignment questions, your SPSS Data file, and your SPSS Output file, your SPSS Data file , and your SPSS Output file.

#### Submission and Grading Information

**To submit your completed Assignment for review and grading, do the following:**

- Click the
**Week 4 Assignment**link. You will also be able to “View Rubric” for grading criteria from this area. - Next, from the Attach File area, click on the
**Browse My Computer**button. Find the first document you want to attach (your Word doc, SPSS Data file, or SPSS Output file) and click**Open**. Repeat this for the remaining two documents. - If applicable: From the Plagiarism Tools area, click the checkbox for
**I agree to submit my paper(s) to the Global Reference Database**. - Click on the
**Submit**button to complete your submission.