"Finally, it combined the real adjusted salary data with the opportunity data, giving double weight to the opportunity data." How do you decide how to combine

"Finally, it combined the real adjusted salary data with the opportunity data, giving double weight to the opportunity data." How do you decide how to combine "adjusted salary data" and "opportunity data"? They aren't even in the same unit. I find that this is often the problem with these city rankings (not only this one, but also "quality of life" or "most expensive city" rankings). There is no universal way to weigh these factors, and your result highly depends on the particular weightages you assign, often arbitrarily.