Chapter 12 Flashcards
What method and statistic is used when testing the equality of three or more population means?
The analysis of variance (ANOVA) technique and F statistic
What are the three assumptions for the ANOVA technique
- Populations follow normal distributions
- Standard deviations are equal
- Populations are independent
Why is ANOVA used instead of testing two populations at a time
build up of type 1 errors
ANOVA term for differing populations being observed
Treatment
The sum of the squared differences between each observation and the overall mean
Total variation
The sum of the squared differences between each treatment mean and the grand or overall mean
Treatment variation
The sum of the squared differences between each observation and its treatment mean
Random Variation
For the ANOVA test, how do we determine the degrees of freedom
For the numerator: Number of treatments (k), -1
For the denominator: Observations (n) -number of treatments.
What is the benefit of considering other factors of variation
we can reduce the error variance
A second treatment variable that when included in the ANOVA analysis will have the effect of reducing the SSE term
Blocking Variable
The effect of one factor on a response variable differs depending on the value of another factor
Interaction Effect
A graph that shows the interaction of two variables
Interaction plot
Blocker variables and treatment variables are called what when testing for interaction
Factors
The outcome variable is called what when testing for interaction
Response
If a blocking variable seems likely to be of the same importance as the treatment variable, what term is used to describe the ANOVA analysis
Two-factor experiment
