But because survey participation is voluntary and can be affected significantly by internal employer branding efforts, rankings on these lists are not truly unbiased. (blog.simplyhired.com)
Unless your breed has a small population and is largely in the hands of club members, encourage survey participation by non-members. (ashgi.org)
In other words, post - survey weighting adjustments reduce bias if the weighting variables are related to (correlated with) the survey measures and the likelihood of survey participation. (memphisinvest.com)