ANOVA stats flashcard
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Who developed the ANOVA?
R.A. Fischer

When can an ANOVA be used?
 In place of the T test for designs with 2 conditions
 Designs with more than 2 conditions
 Designs with more than one IV

What can we view the ANOVA as?
 A model fitting procedure
 AND a hypothesis testing procedure

What is the SS_{total}?
A measure of the variability for scores and residuals around a single mean

What is the SS_{e}?
A measure of the variability of residuals and scores around the mean of each condition

What is the SS_{model}?
The difference between the SS_{total} and SS_{e}

What does the SS_{model} represent?
The signal component in the data (the variability between the condition means)

What are SS_{model} and SS_{e} also known as?
 SS_{between }(groups)
 SS_{within} (groups)

What are the assumptions for the anova?
The same as for any other parametric test (normality an homogeneity)

What are the mean squares (MS) in anovas?
Variances in the data (confusingly)

How do we find the MS?
Divide the SS with the degrees of freedom

What is the DF total?
Total number of scores in the experiment minus 1

What is the DF model?
 The number of experimental conditions 1
 Experimental conditions = k

What is the DF error?
The degrees of freedom for the first condition minus the DF for the second one

What is the F value?
 The test statistic
 Named after Fischer (gay)
 The ratio of the two variances or mean squares
 (MS model over MS error)

What are the degrees of freedom for the F ratio?
The DF for the model and error

When the null is true, what is the expected F value?
1.0

When there is a high F value, what can be inferred?
 An experimental effect is present
 This could be du to chance though

How is the Fdistribution different from the tdistribution?
 It is positively skewed
 Only the upper tail is used when testing hypotheses (even in 2 sided tests)