Analysis of Covariance

1
Analysis of Covariance

• Another Approach

2
Unequal Slopes
3
(No Transcript)
4
Unequal slopes - Another way to write the model
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
Origin in the Anova Table

• What being tested is
• All the intercepts all equal
• this, in most cases, is extreme extrapolation
• who cares about X0
• EMM asks that the lines are equal for X the
  mean of X
• You might want to choose a different X
• SPSS does not allow Post Hoc Tests

10
Weight and OriginWeight In the Anova Table

• Weight - if the sums of the slopes is 0
• OriginWeight is testing is the deltas are zero
• If yes, then all slopes are equal

11
Example

• In this example the slopes are not all equal -
  why?
• What are the three slopes?
• We need the parameter output

12
(No Transcript)