Crop timing vs. noise

I got into the habit of cropping in the raw converter. I had an on going problem w/ noise when generally it should not have been a problem at all. My son was helping me w/ some pp and when he did the crop at the end of editing just before sharpening, this noise problem disappeared to a great extent. Does this sound right and, if so, why is that?? It's nice to know the what and even better to know the why. Thank you.
_______________
Rog
Oh, Using Elements 8.

Cropping doesn't affect noise unless you resample the image. I always crop in the raw converter, you're doing it right.

Cropping and noise are utterly unrelated, but if you are cropping a lot the image that you have left is now smaller and will need to be down sized less when displayed filling the screen. Thus noise that was always there but was concealed by the greater downsizing before the crop will become more visible.