Within-Groups ANOVA

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# Within-Groups ANOVA - PowerPoint PPT Presentation

Within-Groups ANOVA. Chapter 13. One-Way Within-Groups ANOVA. Similar to paired-samples t -tests Same participants do something multiple (more than 2) times Are used when we have one IV with at least 3 levels, a scale DV, and the same participants in each group.

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## Within-Groups ANOVA

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### Within-GroupsANOVA

Chapter 13

One-Way Within-Groups ANOVA

Similar to paired-samples t-tests

Same participants do something multiple (more than 2) times

Are used when we have one IV with at least 3 levels, a scale DV, and the same participants in each group

Benefits of Within-Groups ANOVA

We reduce error due to differences between the groups.

We know that the groups are identical for all of the relevant variables because each group includes exactly the same participants.

We are able to reduce within-groups variability due to differences for the people in our study across groups.

Steps of Hypothesis Testing

Step 1. Identify populations, distribution, and assumptions.

Step 2. State the null and the research hypotheses.

Step 3. Determine characteristics of the comparison distribution.

Step 4. Determine critical values.

Step 5. Calculate the test statistic.

Step 6. Make a decision.

Effect Size

R2 can be calculated for this type of ANOVA, too!

Post hoc test to identify where you have differences if your F is significant

You need to calculate the standard error before using the Tukey HSD test

Tukey HSD
Matched groups use different people who are similar on all of the variables that we want to control.

We can analyze our data as if the same people are in each group, giving us additional statistical power.

Matched Groups