module 12

Question 1

when do you use a two factor analysis of variance

Answer 1

to evaluate the change in a numerical variable across two categorical variables.

Question 2

What are interactions?

Answer 2

Interaction is when the response to the combination of two levels is not the simple sum of the two.

Question 3

because there is two categorical variables, you look at the effect each level as on the ______ variables and the interaction between the _________ variables

Answer 3

numerical, categorical

Question 4

categorical variables are called ____ and different types within them are called ____

Answer 4

factors, levels

Question 6

intersections of factors and levels is called a _______

Answer 6

cell

Question 7

null distribution for main effects A

Answer 7

sampling distribution from repeatedly sampling a statistical population where the means are the same across all levels of factor A.

Question 8

null distribution for main effects B

Answer 8

sampling distribution from repeatedly sampling a statistical population where the means are the same across all levels of factor B

Question 9

null distribution for interactions

Answer 9

sampling distribution from repeatedly sampling a statistical population where the cell means are additive

Question 10

F-tests in a two factor ANOVA work by partitioning data into what four sources of variation

Answer 10

• group variation factor A (MSa) variation among means of levels in factor A
• group variation factor B (MSb) variation among means of levels in factor B
• AB interaction (MSab) varition attributable to deviation from additivity
• Residual variation (MSe) variation among sampling units within a cell

Question 11

three f tests built around different ratios of the sources of variation

Answer 11

• main effect A (F=MSa/MSe)
• main effects B (F=MSb/MSe)
• interations (F=MSab/MSe)

Question 12

for all f-tests the null and alt hypotheses are:

a) Ho: F≤1 and Ha: F>1
b) Ho: F=1 and Ha: F≠1
c) Ho: F≤1 and Ha: F<1

Answer 12

a)