Feminists epistemologists have often remarked on errors due to androcentrism– the tendency to mistakenly take the male as the norm. It seems a bit of this went into the calculations convincing the UK government that their education plans would save money:
12. Some of the output from the model used to estimate the RAB looks optimistic. For example, the average male graduate earning is assumed to increase to £99,500 pa (in real terms, at 2016 prices) by the end of the repayment period. Looking into how the estimates were made, we have been able to make some suggestions as to why they are high. For example the model assumes equal numbers of male and female graduates; the reality is that there are many more female graduates than male, and on average females earn less.
From the executive summary posted here.