Line Width was the problem. I tested several line widths and the smaller the line width the closer the object gets to the correct size. Unfortunately, with my very old version of Adobe illustrator (CS2), I can’t figure out how to get the line width to go less than 0.25 pt. But at least I understand the problem and I can compensate if I need accuracy closer than the 0.0035 inch error I get with a line width of 0.25 pt.
Thanks for all the comments.