Sweet, I hope they find it. It sucks dealing with those smells, especially in hot weather.
From past experiences, if you give them the general direction the smell is coming from, animal control is usually pretty good at finding the carcass, but if someone else knows where it is, it makes things much easier.
The table of contents at the beginning of the report has a link to the methodology. Here’s the methodology for this study:
https://www.pewresearch.org/internet/2023/10/18/data-privacy-methodology-2/
Towards the bottom there is an image with the info you need.