Men and women ask for pay increases at the same rate, according to a new study, which seems to debunk one of the most common explanations cited for the persistence of a gender wage gap.

Using data collected from 4,600 Australian workers across more than 800 employers, the study from the University of Wisconsin in the US and the University of Warwick and Cass Business School in the UK found “no difference” in the likelihood of asking between the two genders. A lack of assertiveness in negotiations is often cited as a potential reason why women might make less money than men for similar work.

Researchers say the finding is important because it bucks against a theory that “places some of the responsibility for the existence of gender differentials upon female employees and the choices they make”, rather than structural biases.

According to the World Economic Forum, there is no country on earth where women make as much as men for the same work. WEF research has predicted that it will take 81 years at current rates of improvement for women to reach parity.

“We didn’t know how the numbers would come out. Having seen these findings, I think we have to accept that there is some element of pure discrimination against women,” said study co-author Andrew Oswald, a professor of economics and behavioural science at the University of Warwick.

Oswald said that Australia was the “natural” testing place for these theories because “it is the only country in the world to collect systematic information on whether employees have asked for a rise [in pay]”. The gender pay gap in Australia is about 17%, slightly lower than the 21% gap that exists in the US.

The study also claims to disprove the notion that part of the reason women don’t ask for raises is that they are more likely to be sensitive to the harm that such requests could have on their inter-workplace relationships.

Researchers did find, however, that younger women received raises just as often as younger men.

“This study potentially has an upside,” said co-author Dr Amanda Goodall a professor at Cass Business School of the City University of London. “Young women today are negotiating their pay and conditions more successfully than older females, and perhaps that will continue as they become more senior.”