there is a major deficiency in Levels data, as they accept a combination of offer letters, W-2's and Yearly Compensation Statements. So for positions with heavy share based compensation combined with market volatility, the W-2's and can be wildly different than an offer letter. This winds up wasting everyone's times, inflated expectation from every starry eyed employee, and bad data in general. There isn't enough data to smooth that out, for most positions or time frames.