Many companies do in the sense that you can often find out a range from the recruiter although the information isn't usually published in the ad. There's some push in certain states and countries to change this but I'm not that convinced that it's a significant/positive change. I guess we'll see.
If you need it for research, just about any dataset you collect will be biased in some way - you just need to be aware of how it's biased for your analysis.
If you need it for research, just about any dataset you collect will be biased in some way - you just need to be aware of how it's biased for your analysis.