The Paula Principle: Five reasons women do not get the same job opportunities as men

And how much of the reason comes down to women’s own choices?

Discrimination, psychology and structural barriers all feed into the problem (Getty)

Have you ever wondered why, as an intelligent and educated woman who does what you are told and works hard, you are not progressing as fast as you’d like?

Girls and women are outranking boys and men more and more when it comes to education at school and university, yet that success does not generally translate into equal opportunity for women in the workplace.

According to a theory and soon-to-be-published book called the Paula Principle, developed by professor Tom Schuller, there are five factors that may be contributing to women’s current inequality and frustration.

These factors are not listed in order of importance – it will depend on a woman's "particular context, on the sector or organisation or society you live in, and what community you live in" said Schuller.

Either way, a lack of diversity in companies is costing the economy "billions of pounds".

“I have found, to an extraordinary degree, that people from all walks of life latch onto one or all of these factors and say, ‘Yeah for me, this is the one that really rings bells’ or ‘I’ve had particular experience of that one’.”

1. Discrimination, covert or overt

Whether you've experienced sexual harassment, a corporate outing to a strip club or are called "young lady” in the office, sexism is pretty common in 2017.

Schuller said there was less overt discrimination today than several decades ago, but there was "still plenty around", including when women become pregnant.

2. Structural reasons

Women are more likely to take care of their children, or look after elderly parents. Combined with the rising costs of childcare, there are various barriers which hinder women from reaching the top jobs.

3. Psychology

It appears the old adage remains true: a woman will see one skill on a job spec that she does not feel confident about and ditch her application, while a man will apply for the same job based on the one skill that they do have.

4. Vertical network

Because the top levels of most sectors are already dominated by men, there are plenty of people that younger men can relate to and receive a helping hand from as they climb up the ladder. Schuller describes this network as “PLUs” – people like us. Sectors that are dominated by women, such as teaching and nursing, tend to be underpaid relative to other sectors.

5. Positive choices

This is the most controversial point but, as Mr Schuller said, the most interesting one to grapple with.

Men might generally cling onto the greasy pole of higher management, but women are more likely to weigh up their work/life balance.

Women will ask themselves: “Do I need the money? Do I need the status? Am I still developing in the job I’m in?”

“If the answers are no, no and yes, their choice to continue in their current role or move sideways might be sensible and rational,” he said. “Men could benefit from some of this thinking too.”

But how much positive choice means women are to blame for their own lack of upwards mobility?

Schuller replied that "everyone needs to make tradeoffs".

“I mean a genuinely positive choice,” he said. “So if it [their decision] harms them in some way, then it might not be a sensible choice.”

That does not quite answer the conundrum of a culture of presenteeism: If you take your lunch break every day, you might be less likely to get a promotion. And you’re more likely to hang around past 7pm, even if all you’re doing is liking your friend’s status on Facebook.

If all barriers for women are deconstructed, there will still be many people who choose a lower level job, said Schuller.

“There are lots of women who have careers and want to progress but that doesn’t mean they will become CEOS or top judges,” he said. “They want to develop in their work, but not necessarily in a vertical sense."

The main aspect of today’s culture that needs to change to bring about gender equality in the workplace, said Schuller, is scrapping the binary definitions of full-time and part-time work. The UK government's website says that a full-time worker typically works 35 hours per week.

We need to eliminate the concept that if you work part time, you are not fully committed to your career, he said.

“Things will really only open up for women in terms of roles of competence when men have mosaic careers, and they do not subscribe to this full-time pattern,” he said.

“Companies should enable people to have a wider range of choices.”