Sharon Zollner talks about returning to work full-time, stepping up to become chief economist of the country's largest bank and the challenges with trying to predict where the economy will go next.

Sharon Zollner believes the key to being a good economist is to tell the story behind the numbers.

The 42-year-old this week stepped up to become chief economist of the ANZ - the country's largest bank.

It's a major shift for Zollner who will work full-time in the role for the first time since having children.

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Zollner has been with ANZ since 2010 in a part-time capacity, balancing her career as a senior economist with looking after her two boys who are now seven and nine.

As chief economist she will be accountable for the final say on economic policy at the bank including the all important forecast on whether the Reserve Bank will cut or hike the official cash rate.

"It is a very high profile call and is important for the dealers. One person has to own that - for good or ill."

The Reserve Bank is expected to hold the cash rate - currently at a record low of 1.75 per cent - until late 2018 or mid 2019.

"So I've got a bit of time to get my feet under the desk."

But inevitably there will be winners and losers when it comes to predicting the first shift in the rate.

"I'm sure at that point I will feel exposed."

But Zollner says economic forecasting is really hard and "everybody gets it wrong".

"Being an economist is essentially about telling a story and talking about the risks and why things might not pan out.

"There is a lot of uncertainty. It is not helpful to pretend that doesn't exist."

Zollner, who grew up in Methven on a cropping farm, first became interested in economics at Canterbury University.

"At its heart economics is about people and the decisions they make. People think it is about money."

But she says there are plenty of economic decisions people make that don't involve money.

Zollner began her career at the Reserve Bank in Wellington before taking a two-and-half year secondment to work at Norway's central bank.

It helped that she already spoke fluent Danish after spending a year living in Denmark on an exchange programme before going to university.

Her drive to take up a secondment at the Norwegian central bank also stemmed from the desire to travel.

"I wanted to do an OE before I turned 30."

The Norwegian central bank was looking for someone to help with a new inflation targeting model and the Reserve Bank of New Zealand just happened to be one of the first banks to use inflation targeting.

Low inflation in recent years has proved a major challenge for central banks and has prompted calls in New Zealand for the Reserve Bank's cash rating setting to be linked to employment as well as inflation.

Models can bring discipline to people's thinking but they need to be taken with a grain of salt because the world is a complicated place and is always changing, Zollner says.

"If you rely on them too much you will probably miss the most important stuff which is something you haven't seen before."

Living in Norway was an eye-opener where the high level of wealth meant it was not uncommon for senior managers to leave work at 3pm to pick up their children from school.

With its generous parental leave provisions women took extended time off to have children but then came back to work full-time - and that was the expectation.

Zollner says New Zealand is more flexible in that parents can come back part-time or stay at home permanently.

"Where as Norwegians - if they choose to stay home or not work full-time they are seen to be letting the side down."

After Norway Zollner returned to Wellington - shortly after which she met and married her husband.

In 2006 she left the central bank to go to Westpac's institutional arm in her first move into the private sector.

But when Westpac moved its dealing room to Auckland she took redundancy to stay in Wellington where her husband had a good job.

In 2010 Zollner started work at ANZ after her husband got a job in Auckland and the family moved north.

Zollner's move into the role will mean it is the first time ANZ's chief economist will be Auckland based while its six-person team is split across both Wellington and Auckland.

Working part-time at the ANZ has not stopped her from being innovative or thinking outside the box.

In 2012 she came up with the bank's truckometer - a tool which it uses to measure economic activity by the number of heavy and light vehicles on key New Zealand roads.

Zollner says her husband worked for the New Zealand Transport Agency at the time and that "brought it to mind".

She rang and asked him and she could get access to the data.

"It turned out they had the most amazing treasure trove of data," she says. "I felt like I had stumbled across gold nuggets."

More recently she has been expanding her mind by undertaking a course at Udacity - an open learning course spun out of Stanford University's computer science department which specialises in nanodegrees and courses around machine learning and data science.

Looking back to her school days Zollner says she began to think about the road not taken, and decided she wanted to study something to do with coding and IT.

"The subject I loved at school was computer studies," says Zollner, who admits to being a geek at heart.

So she took a course in data science and machine learning.

While a lot of it isn't directly related to her current job - one project involved learning how computers can identify dog breeds from a photo, she says it was more about just having an understanding of how it works.

"Until I had done a course in artificial intelligence it seemed like magic."

Machine learning is a bit of a two-sided coin, Zollner says.

"You learn about how it works but also about its vulnerabilities."

Computers are prone to catastrophic forgetting and the practical is well ahead of the theoretical, she says.

"There is a lot of guesswork when you build these things."

There is a big movement towards using more and more data in business and that will flow into economic data.

"I think we are moving towards getting a read on the economy - on a daily basis. In time the three-monthly reads will seem archaic."

That means there will be a lot less guess work when it comes to the numbers.

But in terms of figuring out the meaning Zollner says she remains sceptical of machine learning and believes people are needed to make sense of it all.

There are also risks to only using data.

If a university uses historical data to help it select current applicants it could find itself building in the racist and sexist results that the data gives from past selections.

"It puts out what you put in," she says.

"One always needs to be aware of the limitations."

Zollner is part of a growing number of high-profile women in economics with Christina Leung at NZIER and Zoe Wallis until recently chief economist at Kiwibank.

But the sector remains male dominated.

Zollner says she does not know why there are not as many women doing economics as men but it could be because it has become an increasingly maths-focused discipline and women have not traditionally gone into maths and science study areas.

She believes the role is much more about story-telling and writing than the numbers - areas which women are good at.

She says in some ways being a woman has opened doors for her as people want to talk to her because she is different.

"If anything it has been an advantage."

Sharon Zollner
• Chief economist ANZ Bank
• Age: 42
• Born and grew up in Methven on a cropping farm
• Educated at Canterbury University Masters in Commerce majoring in economics
• Married with two children

Last movie watched: An Inconvenient Sequel (on a carbon-spewing plane)
Last book read: Lucky Jim by Kingsley Amis
Last overseas holiday: Germany/Netherlands/Denmark with the kids in July, including a week on a hired boat on the lakes and canals north-west of Berlin