title:
  Data from table 3.1, page 39.
  Input 3.4 page 41.
  Output page bottom 41, top 42, output 3.8.
  ** NOTE ** Output does not match because 
    used 0 1 2 for time values.
  ** NOTE ** Manually specifying growth model.
data:  
  file is ch3.dat;
  format is free;
  type is correlation means stdeviations;
  nobservations = 343;
variable:  
  names are y1 y2 y3 age prob; 
  usevar =  y1 y2 y3 age;
analysis:  
  type = general meanstructure;          
model: 
  int    by y1@1 y2@1  y3@1;
  lin    by y1@0 y2@1  y3@2;
  quad   by y1@0 y2@1  y3@4;
  [int lin quad];
  [y1-y3@0];
  y1-y3@0;
  int lin quad on age;