Further ANOVA

Question 1

What are Factorial Experiments?

Answer 1

• Involve two or more independent variables or factors

- all combinations of the IV are tested

Question 2

In a factorial design how many:
F stat
Main Effect
Interactions

Answer 2

• One F statistic for each main effect and interaction
• one main effect for each factor
• one interaction for every combination of factors

Question 3

Give a brief description of the concept of “Interaction in ANOVA”

Answer 3

• An interaction occurs whenever the effect of one IV has an influence on the size of the effect for another IV.
• Interaction can also occur when the differences between the differences in independent variables are different.
• The number of interactions in a design also depended on the number of IV’s.
  
  • for 2 x 2 design, there will be 1 interaction
  • This is the interaction between IV1 and IV2
  • Occurs when effect of one IV changes across the levels of the other IV
• Could also be the effect of one IV, whether a difference between the levels of the IV, changes across the levels of the second IV.
• There is also only one interaction for 3 x3 factorial design, because still only two IV’s,

After more than 2 IV’s, more interactions. Three IV’s would have four interactions, for example