Chap 12 ANOVA Flashcards
Factor
-variable that designates the groups being compared
Levels of the factor
Individual conditions or values that make up a factor
Test wise alpha level
-Type 1 error for individual hypothesis test
Experimentwise alpha level
- several different hypothesis tests
- total probability of type 1 error ( accumulated from the tests)
Error term
= within - group variance
Post hoc tests (posttest)
Additional hypothesis tests are done after an ANOVA
- determine mean differences are sig. and which are not
ANOVA
Analysis of variance
-hypothesis testing procedure that evaluate mean differences between two or more treatment pops.
between treatment variance
the measure of differences between treatment conditions
- the difference between sample means
- -> caused by sampling error (naturally occurring) or treatment effect
within treatment variance
measure of variability within a treatment condition
F-ratio
F= (systematic treatment effects + random, unsystematic difs) / (random, unsystematic difs)
- when there’s no treatment effect F~1.0
- when there’s a treatment effect F»1.0
Square mean
MS(variance)
- mean of the squared deviations
Distribution of F-ratio
- degrees freedom in both the numerator (for between treatment groups) and denominator (within treatment groups)
Eta squared ( η ^2)
Percentage of Variance accounted for by the treatment effect
-(SS between /SS total) *100%
Pair wise comparison
Compare ind. Treatments two at a time
-can lead to accumulated alpha error
Tukey’s HSD test
(honesty significant difference)
-compute min. dif score so that the treatment mean can be considered significant
-therefore can be used to compare two treatment groups
Does it only work for treatment groups with equal n?
