1 / 8

Lesson 7 in SPSS

Lesson 7 in SPSS. How to conduct a single-sample t -test in SPSS. Single-Sample t -Test. Here is a small data set. Notice that we have only one variable containing the scores. Single-Sample t -Test. To begin, choose: Analyze Compare Means One-Sample t-test. Single-Sample t- Test.

bree
Download Presentation

Lesson 7 in SPSS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lesson 7 in SPSS How to conduct a single-sample t-test in SPSS

  2. Single-Sample t-Test • Here is a small data set. Notice that we have only one variable containing the scores.

  3. Single-Sample t-Test To begin, choose: • Analyze • Compare Means • One-Sample t-test

  4. Single-Sample t-Test • Move the variable Scores into the Test variable box • Type the known population mean into the Test Value box. • Click on OK

  5. Single-Sample t-Test The mean calculated from your sample. • The output One-Sample Statistics N Mean Std. Deviation Std. Error Mean Scores 10 81.1000 8.81224 2.78667 The known population mean. One-Sample Test Test Value = 82 t df Sig. (2-tailed) Mean Difference 95% Confidence Interval of the Difference Lower Upper Scores -.323 9 .754 -.90000 -7.2039 5.4039 The significance level. The t-value generated.

  6. Single-Sample t-Test • What does this output tell us? • 1. The mean of our sample data (X) is 81.00 • 2. The known population mean against which we want to test our sample mean is 82.00 • 3. The t-value is -0.323. Why is it negative? Because our formula tells us to take the sample mean minus the population mean. Since our population mean is larger than our sample mean, the t-value will be negative.

  7. Single-Sample t-Test • 4. The significance value is 0.754. When we perform a t-test by hand, we must use a t-table using our selected significance level (a) and our degrees of freedom (n – 1) and then determine if our calculated t-value falls outside the body and into the tails of our distribution. But when we use SPSS, this process becomes much, much easier. All we have to do is look at the significance level. If it is less than our chosen alpha level (0.05), then the test is significant. If it is not less than our chosen alpha level, then the test is not significant.

  8. Single-Sample t-Test • 5. In this case, the significance level of 0.754 is most certainly NOT less than 0.05. Therefore, we fail to reject our null hypothesis of no difference between the sample mean and the known population mean. We conclude, then, that our sample mean of 81.00 is not significantly different from our known population mean of 82.

More Related