title:
  Data from table 3.1, page 39.
  Input 3.7 page 46, modified to add Age -> Prob Behavior
  Figure 3.2 page 45, modified to add Age -> Prob Behavior
  Output bottom page 47 top of page 48
  ** NOTE ** Output does not match because 
    used 0 1 2 for time values.
data:  
  file is ch3.dat;
  format is free;
  type is correlation means stdeviations;
  nobservations = 343;
variable:  
  names are v1 v2 v3 age prob; 
  usevar =  v1 v2 v3 age prob;
analysis:  
  type = general meanstructure;          
model: 
  int  by v1@1 v2@1 v3@1;
  lin  by v1@0 v2@1 v3@2;
  quad by v1@0 v2@1 v3@4;
  [v1-v3@0];
  v1-v3@0;
  age;
  prob on int lin quad age; ! added age here
  [int lin quad];
  int lin quad on age;
  int with lin quad;
  lin with quad;
model indirect:
  prob ind age;