… There is no doubt that such words as 'you ought to do so-and-so' may be used as one's means of so inducing a person to behave a certain way. But if we are to do justice to the meaning of 'right' or 'ought', we must take account also of such modes of speech as 'he ought to do so-and-so', 'you ought to have done so-and-so', 'if this and that were the case, you ought to have done so-and-so', 'if this and that were the case, you ought to do so-and-so', 'I ought to do so-and-so.' Where the judgement of obligation has referenced either a third person, not the person addressed, or to the past, or to an unfulfilled past condition, or to a future treated as merely possible, or to the speaker himself, there is no plausibility in describing the judgement as command. 
Just before Obama took office in 2009, the Department of Labor released a study because, as a deputy assistant secretary explained it, "The raw wage gap continues to be used in misleading ways to advance public policy agendas without fully explaining the reasons behind the gap." The study by CONSAD Research Corp. took into account women being more likely to work part-time for lower pay, leave the labor force for children or elder care, and choose work that is "family friendly" with fuller benefit packages over higher pay. The study found that, when factoring in those variables, the gap narrows to between 93 cents and 95 cents on the dollar.