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Annotated Output | Factorial ANOVA

Computer Output

The tables of descriptive statistics can be used to determine the inferential statistics.

Summary Statistics for the Data: B1
         N       M      SD    Skew    Kurt
A1   4.000   2.000   2.449   0.544  -2.944
A2   4.000   7.000   2.449  -0.544  -2.944

Descriptive Statistics for the Data: B2
         N       M      SD    Skew    Kurt
A1   4.000   6.000   2.449   0.544  -2.944
A2   4.000   5.000   2.449   0.544  -2.944

The descriptive statistics are calculated separately for each group or condition. They are not equivalent to getting the statistics for the variable as a whole.

The tables of inferential statistics show the key elements to be calculated.

Source Table for the Model
                   SS      df      MS
Factor          4.000   1.000   4.000
Blocks         16.000   1.000  16.000
Factor:Blocks  36.000   1.000  36.000
Residual       72.000  12.000   6.000

Hypothesis Tests for the Model
                    F     df1     df2       p
Factor          0.667   1.000  12.000   0.430
Blocks          2.667   1.000  12.000   0.128
Factor:Blocks   6.000   1.000  12.000   0.031

Proportion of Variance Accounted For by the Model
                  Est      LL      UL
Factor          0.053   0.000   0.302
Blocks          0.182   0.000   0.442
Factor:Blocks   0.333   0.019   0.562

For the Factor A Main Effect, F = 0.667, p = .430. This would not be considered a statistically significant finding.

For the Factor B Main Effect, F = 2.667, p = .128. This would not be considered a statistically significant finding.

For the Interaction, F = 6.000, p = .031. This would be considered a statistically significant finding.

For the Factor A Main Effect, partial eta 2 = 0.053. Thus, 5.3% of the variability among the scores is accounted for by Factor A.

For the Factor B Main Effect, partial eta 2 = 0.182. Thus, 18.2% of the variability among the scores is accounted for by Factor B.

For the Interaction, partial eta 2 = 0.333. Thus, 33.3% of the variability among the scores is accounted for by interaction of Factor A and Factor B.

For Factorial ANOVA, the confidence intervals around (centered on) each mean are appropropriate but not provided in the output.

APA Style

The Factorial ANOVA provides statistics for the main effects and interactions in a factorial design. Each effect would be summarized in a style analogous to a One Way ANOVA.

A 2 (Factor A) x 2 (Factor B) ANOVA indicated a small and non-statistically significant main effect for Factor A, F(1,12) = 0.67, p = .430, partial η2 = .05, and for Factor B, F(1,12) = 2.67, p = .128, partial η2 = .18. In contrast, the interaction was large in magnitude and statistically significant, F(1,12) = 6.00, p = .031, partial η2 = .33.

Typically, the means, standard deviations, and confidence intervals would be presented in a table or figure associated with this text.