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  • 00:05

    HERSCHEL KNAPP: Welcome to Introductory StatisticsUsing SPSS Second Edition.This video shows how to process the ANOVA test.You can watch the entire video or use the time sliderto navigate directly to any time point.The ANOVA test is similar to the t-test,

  • 00:27

    HERSCHEL KNAPP [continued]: but whereas the t-test compares groups of continuous variablesto determine if one group statistically significantlyoutperformed the other, the ANOVA testcan process three or more groups.In this example, we have three groups.The members of each group will be given a set of instructions

  • 00:47

    HERSCHEL KNAPP [continued]: and asked to assemble the Able Chair.The participants in Group 1 were given text only instructions.Those in Group 2 were given text instructionswith illustrations.And the members of Group 3 were given an instructional videodemonstrating how to assemble the chair.

  • 01:08

    HERSCHEL KNAPP [continued]: The researcher ran the participants individuallyand recorded how long it took each personto assemble the chair.Group 1 had a mean of 97.63 minutes,Group 2 had a mean of 92 minutes,and Group 3 had a mean of 89.77 minutes.

  • 01:28

    HERSCHEL KNAPP [continued]: The ANOVA test will compare the groups to each otherand calculate a P value for each pair of groups.In this three group example, it willcompare Group 1 to Group 2, Group 1 to Group 3,and Group 2 to Group 3.If the P value is less than or equal to 0.05,

  • 01:49

    HERSCHEL KNAPP [continued]: we would conclude that one group statistically significantlyoutperformed the other.The ANOVA test has three pretest criteria, normality, n quota,and homogeneity of variance.We'll check for normality now.

  • 02:10

    HERSCHEL KNAPP [continued]: The other two will be processed when we run the ANOVA test.This example uses the data set Ch06 Example01 ANOVAandKruskalWallisTest.sav.

  • 02:30

    HERSCHEL KNAPP [continued]: This data contains two variables.The first variable is group, whichis a categorical variable containing three values.Group 1 got the text only instructions,Group 2 got text with illustration instructions,and Group 3 got an instructional video.The second variable is time.

  • 02:51

    HERSCHEL KNAPP [continued]: This is a continuous variable thatcontains the number of minutes that each participant requiredto assemble the chair.The ANOVA test will compute the mean for each groupand then calculate the P value for each pair of groups, whichwill tell us which group, if any,statistically significantly outperformed which.

  • 03:15

    HERSCHEL KNAPP [continued]: To check for normality, we need to order a histogramwith normal curve for time for each group.We'll begin with Group 1, the group that was assignedthe text only instructions.Click Select Cases, click If Condition Is Satisfied,and click If.

  • 03:36

    HERSCHEL KNAPP [continued]: In the dialog box, enter group=1.Click Continue.Click OK.Now that only the records for Group 1 are active,we can order a histogram with normal curve.Click Analyze, Descriptive Statistics, Frequencies.

  • 03:59

    HERSCHEL KNAPP [continued]: Move time to Variables.Click Charts.And select Histogram With Normal Curve.Click Continue.Click OK.And it will process.The histogram for Group 1, text only instructions,meets the normality criteria.

  • 04:21

    HERSCHEL KNAPP [continued]: Now, we'll repeat this process for Group 2, textwith illustrations.Click Select Cases.Click If Condition Is Satisfied.And click If.In the dialog box, enter group=2.Click Continue.

  • 04:42

    HERSCHEL KNAPP [continued]: And click OK.Now, that only the records for Group 2 are active,we can order a histogram with normal curve.Click Analyze, Descriptive Statistics, Frequencies.Notice that time is still in variables.Since the charts option hasn't beenchanged since our prior run, we don't need

  • 05:03

    HERSCHEL KNAPP [continued]: to revisit the charts menu.Click OK.And it'll process.The histogram for Group 2, text with illustration,meets the normality criteria.We'll repeat this one more time to process Group3, the instructional video.

  • 05:24

    HERSCHEL KNAPP [continued]: Click Select Cases, click If Condition Is Satisfied,and click If.In the dialog box, enter group=3.Click Continue.And click OK.Now that only the records for Group 3 are active,we can order a histogram with normal curve.

  • 05:47

    HERSCHEL KNAPP [continued]: Click Analyze, Descriptive Statistics, Frequencies.Click OK.And it will process.The histogram for Group 3, the instructional video,meets the normality criteria.Before we run the ANOVA test, we need

  • 06:07

    HERSCHEL KNAPP [continued]: to select all of the records.The simplest way to do this is to click on the filterunderscore dollar sign variable and press the Delete key.To run the ANOVA test, click on Analyze, Compare Means,One Way ANOVA.

  • 06:28

    HERSCHEL KNAPP [continued]: Move time to Dependent List, and move group to Factor.Click Options, and click Descriptive and Homogeneityof Variance Test.Click Continue.Now, click on Post Hoc.

  • 06:48

    HERSCHEL KNAPP [continued]: The Post Hoc menu allows us to select how the groups of pairswill be compared to each other.Since each group has the same number of participants,we'll use the Tukey test.If the groups had different ends,then we'd use the Sidac test instead.Click Continue.Click OK.

  • 07:09

    HERSCHEL KNAPP [continued]: And it will process.We see that each group has an n of at least 30.Hence, the n quote is satisfied.We also see that the homogeneity of variance testreturned a P value of 0.122.

  • 07:30

    HERSCHEL KNAPP [continued]: Since this is greater than 0.05, thisindicates that there is no statistically significantdifference in the variances between the groups.Hence, the homogeneity of variance test is satisfied.Back to the Descriptives table, notice that this table containsthe means for each group.These figures will be useful when it comes

  • 07:51

    HERSCHEL KNAPP [continued]: to documenting the results.Finally, we see the results of the ANOVA test.The P value is 0.001.Since this is less than or equal to 0.05,this tells us that at least one group significantlyoutperformed another.

  • 08:12

    HERSCHEL KNAPP [continued]: To determine which group outperformedwhich, we'll look at the pairwise comparisonson the multiple comparisons table.The first pair we'll assess is the text groupwith a mean of 97.63, and the text with illustrations group,with a mean of 92.The P value of 0.022 is less than

  • 08:36

    HERSCHEL KNAPP [continued]: or equal to 0.05, indicating that the textwith illustrations group statistically significantlyoutperformed the text Group.The next comparison is the Text group, with a mean of 97.63,and the video group with a mean of 89.77.

  • 08:58

    HERSCHEL KNAPP [continued]: The P value is 0.001.Since this is less than or equal to 0.05,this indicates that the video group statisticallysignificantly outperformed the Text group.The last pair of comparisons involves the textwith illustrations group with a mean of 97.63

  • 09:19

    HERSCHEL KNAPP [continued]: and the video group with a mean of 89.77.This comparison produced a P value of 0.536.Since this is greater than 0.05, thistells us that there is no statistically significantdifference in the assembly time between the textwith illustrations group and the video group.

  • 09:44

    HERSCHEL KNAPP [continued]: This concludes this video.

Video Info

Series Name: Introductory Statistics Using SPSS

Episode: 6

Publisher: SAGE Publications, Inc.

Publication Year: 2017

Video Type:Tutorial

Methods: Analysis of variance, SPSS

Keywords: instruction manuals; mathematical computing; mathematical concepts; Software

Segment Info

Segment Num.: 1

Persons Discussed:

Events Discussed:

Keywords:

Abstract

Professor Herschel Knapp discusses the use of ANOVA in statistics. He demonstrates each step in running a report in SPSS and analyzes the results.

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ANOVA

Professor Herschel Knapp discusses the use of ANOVA in statistics. He demonstrates each step in running a report in SPSS and analyzes the results.

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