Lecture 7, April 13th Flashcards

What is omega squared?

An estimate of the proportion of variance in the population that can be accounted for by the IV

How is omega squared calcuated?

What is the formula of a statisitcal model for One-Way Independent Groups ANOVA?

How is the formula of a statisitcal model for One-Way Independent Groups ANOVA calculcated?

What is the relationship between t & F?

A t-test is the difference between means divided by the difference expected by chance

An f stat is the difference of the variability between treatments divided by the variability within treatments

What is Repeated Measures ANOVA?

Used to find out whether there is a significant difference between the means of two or more groups when the same participants are in each group

What is the formula of a statisitcal model for One-Way Repeated Measures ANOVA?

How is the formula of a statisitcal model for One-Way Repeated Measures ANOVA calculcated?

What are the overview of steps to calculate a One-Way Repeated Measures ANOVA?

1. State the hypotheses (H₀ & H₁) in words and symbols

2. Calculate the sums of squares (SS_total, SS_treatment, SS_subjects, SS_error)

3. Calculate the degrees of freedom (df_treatment, df_error, df_subjects, df_total)

4. Calculate mean squares (MS_treatment, MS_error)

5. Calculate F-ratio

6. Construct a summary / source table

7. Use F-table to find F_crit (based on df)

8. Make a decision i.e. compare F_obtained to F_crit

9. Interpret results

What are some assumptions of both Independent Groups and Repeated Measures ANOVA?

• Normality

  • Scores are approximately normally distributed around each group mean

• Homogeneity of Variance

  • The groups have equal variances, especially if group sizes are close to equal

What are some assumptions for Independent Groups ANOVA?

• Independence of Observations

  • Groups in the study are made up of different people and any participant cannot influence another

What are some assumptions for Repeated Measures ANOVA?

• Homogeneity of Covariance

  • Refers to how much people’s scores in one condition correlate with their scores in another. If scores are coming from the same people, they should follow the same patterns across conditions

Where is Independent Groups ANOVA more significant?

• When each participant serves in only one condition

• Analyses between-groups variance relative to within-groups variance (variance due to individual differences + error)

Where is Repeated Measures ANOVA more significant?

• When every participant serves in every condition

• We calculate and remove any variability due to individual differences between participants

• Analyses between-groups variance relative to within-groups variance (tends to be smaller - variance due to individual differences removed)

What are the advantages of Repeated Measures ANOVA?

• Error variance is smaller as opposed to Independent Groups ANOVA, which increases the F_obt and therefore makes the results more powerful

• Likely to detect an effect (if one exists) with the same number of data points

• Fewer participants are needed to detect an effect

What are the disadvantages of Repeated Measures ANOVA?

• Order / carry-over effects, whereby experiencing one condition effects the results of other conditions (could be due to order of conditions, fatigue, etc.)