{"id":159,"date":"2019-07-16T20:36:31","date_gmt":"2019-07-16T20:36:31","guid":{"rendered":"http:\/\/blogs.ubalt.edu\/jboettinger\/?p=159"},"modified":"2020-02-13T09:42:04","modified_gmt":"2020-02-13T14:42:04","slug":"using-spss-comparing-means-repeated-measures-one-way-anova","status":"publish","type":"post","link":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/2019\/07\/16\/using-spss-comparing-means-repeated-measures-one-way-anova\/","title":{"rendered":"Using SPSS: Comparing Means – Repeated Measures One-Way ANOVA"},"content":{"rendered":"

This post will be about finding a difference in means when it comes to repeated measures in research designs with a factor with more than 2 levels. Just like with the Repeated Measures t-test<\/a>, we’ll be lining our levels up in columns. For this example, we’ll pretend that we’ve collected data on self-reported depression. Participants were asked to rate on a scale from 1-9 how severe they felt their depression is. They were then given medication to take which is known to reduce depressive symptoms. Participants were asked again after 6 months how high they rated their depression. They were asked one last time at the end of 12 months.<\/p>\n

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I went ahead and named the levels in the Variable view.\"\"<\/p>\n

To run the actual test, simply go up to Analyze, scroll over General Linear Model, and click Repeated Measures.<\/p>\n

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A pop-up will appear. In the first box, create the name of your factor. In this case, I’ve named it time, because we’re doing comparisons across time. In the second box, I typed in 3 because we have 3 levels and then I pressed Add. In the third box, I named our dependent variable and clicked Add. Next, we need to Define our factors…<\/p>\n

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Another pop up will appear. Move the levels over into the top, right box. I prefer doing this in chronological order from top to bottom. Then, click Options.<\/p>\n

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I would recommend getting means for everything, so move OVERALL and time over to the box on the right. I also recommend clicking the Descriptive Statistics and Estimate of Effect Size boxes. Finally, click the Compare Means checkbox; it’s located under the big, white box on the right. Click all the Continues and OK’s that follow.<\/p>\n

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We can see from the means that the average for Start is greater than at 6 months is greater than at 12 months. This is important to know, but this does not prove significance.<\/p>\n

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Go to the Tests of Within-Subjects Effects box and find “time” on the left, scroll over to Greenhouse-Geisser, and then scroll all the way to F and significance. We have a huge F score of 68.5 and a significance which is less than 0.05 and so we can say that somewhere there is a significant difference in the groups. If you need to report the effect size, you can find it under Partial Eta Squared.<\/p>\n

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This last box shows us the post-hoc under Pairwise Comparison. As you can see, all the comparisons are significantly different with a significance less than 0.05. This means that we can say that there was a significant difference in times since treatment began with participants expressing the most depression before the treatment started, less depression 6 months after the treatment started, and the least depression after 12 months of treatment.<\/p>\n

\"\"<\/p>\n","protected":false},"excerpt":{"rendered":"

This post will be about finding a difference in means when it comes to repeated measures in research designs with a factor with more than 2 levels. Just like with the Repeated Measures t-test, we’ll be lining our levels up in columns. For this example, we’ll pretend that we’ve collected data on self-reported depression. Participants […]<\/p>\n","protected":false},"author":1347,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[151,150,147],"tags":[4,3,5,7,6,84,117],"_links":{"self":[{"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/posts\/159"}],"collection":[{"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/users\/1347"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/comments?post=159"}],"version-history":[{"count":3,"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/posts\/159\/revisions"}],"predecessor-version":[{"id":581,"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/posts\/159\/revisions\/581"}],"wp:attachment":[{"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/media?parent=159"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/categories?post=159"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.ubalt.edu\/mathsupportcenter\/wp-json\/wp\/v2\/tags?post=159"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}