The purported gender pay gap, which supposedly shows that men earn more than women is an perfect example of the use of statistics to trick people into a simple, but false, conclusion: that female employees are discriminated against. Yes, it is true that you average across all employees, women earn less than men - and this is the figure quoted as the gender pay gap. There are two major problems with its calculation and inference as to cause.
1) It does not compare like with like.
For example, it does not take into account the different jobs people do (or perhaps choose to be in) and does not take into account differential levels of training, education and experience. This is the difference between the unadjusted (and most frequently referred to) and the adjusted pay gap (which is much narrower). Furthermore, none of the metrics used take into account ability. Equal ability is assumed, never demonstrated. As far as I'm aware, there has never been a serious attempt to correct for differential ability.
2) It may reflect choices, not discrimination.
It is clear from the statistics that the majority of the pay gap emerges once couples have children. More women than men take on childcare responsibilities, which involves exit from the labour market for a period of time - and often return only part time. These facts account for the vast majority of the unadjusted pay gap. It is unclear (but in my view likely) that more women wish to take on childcare responsibilities than men - therefore the pay gap may reflect life choices, not discrimination.
Pay gap in young workers
In young workers in the UK, the unadjusted pay gap is low, and possibly favours women. It is unclear what direction
Women in their twenties earn more than men
https://www.theguardian.com/money/2015/aug/29/women-in-20s-earn-more-men-same-age-study-finds
Women earn more than men up to age 35
http://www.dailymail.co.uk/news/article-2957178/Women-earn-men-35-gender-pay-gap-reverses-end-earning-35-less.html
Gender pay gap down to 5% among UK workers in their 20s, study finds
https://www.theguardian.com/society/2017/jan/04/gender-pay-gap-down-to-5-among-uk-workers-in-their-20s-study-finds
Adjusting for occupation, age etc - pay gap overall reduces significantly
https://www.recruitment-international.co.uk/blog/2016/03/uk-women-earn-5-dot-5-percent-less-than-men-according-to-glassdoor
Pay gap widens after birth of children
The vast bulk of the unadjusted pay gap occurs after the birth of children.
https://www.theguardian.com/money/2016/aug/23/gender-pay-gap-average-18-per-cent-less-uk-women
https://www.ifs.org.uk/publications/8429
https://www.ifs.org.uk/uploads/publications/bns/bn186.pdf
https://www.tuc.org.uk/sites/default/files/Pay_and_Parenthood_Touchstone_Extra_2016_LR.pdf
Data Sources
Tools
http://www.equalpayportal.co.uk/tools/
To read
http://www.dailywire.com/news/7985/7-facts-show-women-are-not-victims-pay-amanda-prestigiacomo#
http://www.bbc.co.uk/news/magazine-37198653
http://uk.businessinsider.com/statistics-on-the-gender-pay-gap-for-men-and-women-2016-3
Important: https://fullfact.org/economy/age-motherhood-gender-pay-gap/#
http://uk.businessinsider.com/institute-for-fiscal-studies-statistics-on-the-gender-pay-gap-2016-9
Fathers
Fathers paid more than childless men.
https://whiteandcompanyltd.co.uk/tuc-study-finds-significant-wage-gap-between-working-fathers-and-childless-men/
https://www.tuc.org.uk/sites/default/files/Pay_and_Parenthood_Touchstone_Extra_2016_LR.pdf
US Gender Pay Gap
Among post-PhD workers, women on average earn less. But the gap narrows after controlling for the field the PhD was taken in - and disappears if you look at childless women
http://www.nature.com/news/why-women-earn-less-just-two-factors-explain-post-phd-pay-gap-1.19950
