Module 11: Single Factor ANOVA Flashcards
F test use
-evaluate difference in variance in 2 groups
F test ratio of variances (f score)
-Fo: s2a / s2b
-s2a is for variance in first group
-s2b is for variance in second group
F test null and alternative
-Ho: F =1
-Ha: F =/ 1
F test null distribution shape
- f distribution
-looks more like a chi squared test
F test degrees of freedom
-dfa: na - 1
-dfb: nb -1
-na is for number of sampling units in group a
-nb is for number of sampling units in group b
F test reporting
-mean, SD, and sample size for each group
-observed f score (2 decimal places)
-degrees of freedom
-p value
Single factor anova use
-one numerical and one categorical variable
Sources of variation for ANOVA
-residual variation: variation among sample units within a categorical level
-group variation: variation among categorical levels
ANOVA f score
-compares residual variation to group variation
-F0= group variation / residual variation
ANOVA null and alternative
-statement of means: written first
-Ho: u1 = u2 …
-Ha: u1 =/ u2 …
-f test written second
-Ho: f <= 1
-Ha: f > 1
F score null distribution shape
- f distribution
ANOVA degrees of freedom
-dfg: k - 1
-dfe: n - k
-k is for number of levels in categorical variable
-n is for total sampling units
ANOVA reporting
-mean, SD, and sample size for each group
-observed F score
-degrees of freedom
-p value
TukeyHSD test
-compares means of all possible differences