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• 00:00

[MUSIC PLAYING][An Introduction to the Paired t Test]

• 00:11

DR. HERSCHEL KNAPP: Hi, I'm Dr. Herschel Knapp.[Herschel Knapp, PhD, MSSW.] This video provides an overviewof the Paired t-Test.Now, unlike the t-Test, which gathers datafrom two separate groups, the Paired t-Testmeasures a single group twice, usingthe pretest and a posttest, before and after a treatment.This will help us to determine if there's

• 00:31

DR. HERSCHEL KNAPP [continued]: a statistically significant change in the scoresfrom pretest to posttest.So our research question here could be,is an antidepressive treatment effective?For example, we'll give all of our participantsthe Acme depression test, where 0 is no depression and 100is highest depression.And we'll give them this same test

• 00:53

DR. HERSCHEL KNAPP [continued]: before and after the antidepressive treatment.[Is the antidepressive treatment effective?]Now, here's our group.We have our pretest.We give it to all of our members.Then we administer the treatment.And then we have the posttest and were-administer the same metric to the same people a second time.

• 01:15

DR. HERSCHEL KNAPP [continued]: The Paired t-Test is going to make a comparisonfrom the pretest for each individualto the posttest for each individual.Finally, the Paired t-Test is goingto produce a mean for each group.The depression level mean for the pretest group is 80and for the posttest group, it's down to 65.

• 01:36

DR. HERSCHEL KNAPP [continued]: The Paired t-Test is going to answer the question,is this a statistically significant improvement?So we have our comparisons, one mean against the other.And we get a p-value.In this case, it's 0.031.Our interpretation is that since the p-value isless than or equal to 0.05, we conclude that the treatment was

• 01:59

DR. HERSCHEL KNAPP [continued]: effective in significantly reducing depression,from pretest, with a mean of 80, to posttest, with a mean of 65.Now, suppose we rerun this.And this time, the posttest score mean is 77.In this case, we get a p-value of a 0.452.

• 02:19

DR. HERSCHEL KNAPP [continued]: Since the p-value is greater than 0.05,we'd conclude that the treatment wasineffective in reducing depression,from pretest of 80 to posttest of 77.It's slightly lower, but not low enoughto be statistically significant.[Conclusion]

• 02:42

DR. HERSCHEL KNAPP [continued]: For further details on conducting the paired t-test,please download the videos at sagepub.com/knapp.For further reading, please referto Introductory Statistics Using SPSS, or Practical Statisticsfor Nursing Using SPSS, both by Herschel Knapp.

### Video Info

Publisher: SAGE Publications Ltd

Publication Year: 2017

Video Type:Tutorial

### Segment Info

Segment Num.: 1

Persons Discussed:

Events Discussed:

Keywords:

## Abstract

Dr. Herschel Knapp introduces the paired t-test. The paired t-test measures a single group twice, before and after a treatment, to determine if there is a statistically significant change. For example, Knapp uses the paired t-test to determine if a treatment for depression is effective.