dataframe (with columns grade, jobID, salary_x_ctrl, salary_others, n_x_ctrl, n_others, paygap, confidence) , where "confidence" is one of the following: NA = not available (numbers are too low), "" = no bias detectable, "." = there might be some bias, but we're not sure, "*" = bias detected wit some degree of confidence, "**" = quite sure there is bias, "***" = trust us, this is biased.