I have set up a 5.5 inch square and then adjusted my "factor" in increments of 0.00200 for 10 steps centered approximately at 5.5 inches. Calculated the linear regression for both X and Y. Then calculated the "factor" for 5.5. When I run the 5.5 inch square using the calculated factor I end up with a square that is 5.5185 on the X axis and 5.5045 on the Y axis. THEN when I make a 0.75 inch circle I end up with 0.7320 on the X axis and 0.7340 on the Y axis.

It doesn't make sense to me to be larger on the square and smaller on the circle.

Any thoughts?