Discriminant Factor Analysis

Question 1

Examples of questions that can be answered by DFA

Answer 1

How well can a monkey telling the meaning of a conspecific call? Fundamental frequency, number of harmonics
Which measures predict group membership? Income, social exclusion

Question 2

How do we formally assess DFA

Answer 2

1. The same as MANOVA: Wilks lambda, Hotelling’s Trace, Pillai’s trace and Roy’s largest root
2. Discrimination function coefficients show relative contribution of each predictor variable
   standard coefficients –when we pretend all the variables are N(0,1)–should be used for this part of the interpretation
3. Use a simple descriptor of discriminant function analysis performance
   what proportion of cases are successfully predicted
4. compare accuracy to what we would get by chance
   Default chance (prior) = equal probability of being in any group
   Can change this if theoretically expect different odds