Having skimmed the study summary, I suspect that even more than sampling bias is research design shenanigans. There are a lot of new measures being introduced. They’ve somehow finessed the numbers so that India ranks high on “employee well being” despite having high levels of burnout, worse healthcare outcomes, and lower happiness than many other countries. The study repreatedly says that this new measure of “holistic health” is independent of those other factors.

I suspect that this is less about genuine scientific concern for “well being” and more about guiding businesses with their hiring decisions.