I loved math until it betrayed me in calc 3. but I still dabble in meaningless number play. give me a good standard deviation spreadsheet and there I go trying to make sense or of nothing. so I appreciate what you did here.

Mr initial feeling is that your regression line is not where i would have put it, but I presume the computer made that decision.

I constrained the line to have a zero intercept, without the constraint the intercept is around -900. Implications very light lens might be free

There are actually several parallel lines, post 2005 vs 2005 and earlier. I am sure that there are other factors (zoom vs prime) ....

A couple of key learnings for me:

1. Around 2005 Canon had a major change in their price strategy

2. Price is protional to size (weight).

And remember what Twain said, "There are lies, damn lies, and statistics"