----- Forwarded message from Rich Ulrich -----
Here is my own numeric version for Pre-Post scores,
instead of an ASCII picture.
Model A: scores (1,2,3,4,5) are *shifted* by 3 points each, to
(4,5,6,7,8).
Model B: scores (1,2,3,4,5) are each expanded 3-fold, to
(3,6,9,12,15).
----- End of forwarded message from Rich Ulrich -----
Linear regression will model both of these perfectly. Looking for a
constant difference amounts to forcing the regression slope to be 1.
Looking for a constant multiplier amounts to forcing the intercept to
be 0. You should not do such forcing unless yyou are quite sure it
makes sense. A better and more general approach might be to use
regression and test beta-0=0 and/or beta-1=1.
_
| | Robert W. Hayden
| | Work: Department of Mathematics
/ | Plymouth State College MSC#29
| | Plymouth, New Hampshire 03264 USA
| * | fax (603) 535-2943
/ | Home: 82 River Street (use this in the summer)
| ) Ashland, NH 03217
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