ANOVA

Question 1

How do you put data into SPSS for an ANOVA for a within vs a between subject design?

Answer 1

• Within: ACROSS
• Between: DOWN

Question 2

A One Way ANOVA can compare ____ or more independent groups

Answer 2

• 3
• One IV
• All means should be equal for each Tx group starting out (X1, X2, Control)

Question 3

What is the F test?

Answer 3

• how much observed variability is explained by treatment means and how much is attributed to unexplained differences among subjects
• Also known as sum of square
• The bigger the F, the smaller thr p-value! This is what we want!

Question 4

We do not like ____ in subjects for an ANOVA

Answer 4

variability

Question 5

Total variability attributed the to the treatment effect (between groups) and the unexplained sources of ____ among subjects (within groups).

Answer 5

• variance (error variance)

Question 6

F tests are ____ tailed

Answer 6

• 1
• Only tell us the difference between at least two of the means

Question 7

If the F is found to be large, what must be performed?

Answer 7

A post-hoc test to determine where the difference lies

Question 8

Is this significant?
(F(2,12)=8.67,p-value<0.05)
(F(df, df = F=statistic, p-value)

Answer 8

Yes!

F equal or less than 1 is NOT significant

Question 9

When looking at the SPSS value of ETA we want an effect size of ____ to know it is significant

Answer 9

Greater than 0.14

Question 10

Two Way ANOVA

Answer 10

• Involves** two** independent variables (each variable is a factor and is not repeated).
  Ex:
• Effect of prolonged vs. quick stretch vs. control
• At the same time we are examining knee position (flexed vs. extended).

Question 11

This is an example of…

Answer 11

A 2 x 3 ANOVA

Question 12

Main effect

Answer 12

• Collapse factors (pooling) to get marginal means
• Look at one factor at a time

Example
* Main effect for type of stretch (prolonged vs. quick vs. control) irrespective of knee position.
* Main effect for knee position (flexed vs. extended) irrespective of type of stretch.

Question 13

Interaction Effects

Answer 13

• Look at combinations of levels of each independent variable
• Must plot!
• If parallel, NO interaction

Question 14

How would you interpret this graph?

Answer 14

No interaction, possible main effect

Question 15

How would you interpret this graph?

Answer 15

• Likely an interaction effect

Question 16

An interaction is a significant difference between ____

Answer 16

• simple effects
• Examination of combinations of Tx’s

Question 17

when no interaction, discuss ____
If interaction, no significant main effects, discuss ____
Harder to interpret with interaction present and significant main effects!!! Look at ____ and ____

Answer 17

• main effects
• interaction
• Disordinal interaction
• Ordinal interaction

Question 18

What is this considered?

Answer 18

• Disordinal interaction
• Cannot draw any conclusions about the main effect of knee position. Ignore interpretation

Question 19

What is this considered?

Answer 19

• Ordinal interaction
• Relative ranking of level of stretch does not change with knee position.
• The relative ranking of factor A (Type of Stretch) does not change with factor B (Knee Position). Prolonged stretching better.

Question 20

If a two way ANOVA is significant, what must be run?

Answer 20

post-hoc test