It was bit like insisting pigs are able to fly, no question about it. We all know they can't and anyone who is adamant they can could be dismissed as a porcine prig.

But it was that sort of instance that had Jacinda Ardern on the mat at Parliament and with good reason.

She had been interviewed on the Mike Hosking breakfast show yesterday and for those of us listening, we couldn't believe our ears.

The question was simple enough: The GDP numbers on Thursday, have you seen them, or got a hint?

Ardern: Sorry the, sorry the?

Hosking: The GDP numbers Thursday.

A: GDP numbers, ah yes, we'll be putting out the audited and final results soon.

H: So you have seen them?

A: I get a hint yes.

H: Are they good?

A: I'm pretty pleased.

Hosking then went on and asked about figures that could only be related to the GDP.

On the back of Ardern's comments the markets that David Lange used to refer to as demented reef fish reacted, the dollar rose.

It's for that very reason that the GDP figures are never released in advance, any comment on them can cause all sorts of ructions in the financial markets.

On her way into her caucus meeting, Ardern said she was talking about the Crown accounts which indicates one of two things, she wasn't listening to the question, even if she did ask for it to be clarified and for the second time got GDP, or she didn't understand the difference between GDP and the Crown accounts.

It's a little too cute to say that it's not the first time that Hosking and her haven't been listening to each other properly.

Regardless it's economically dangerous for someone in her position to give an opinion on something that can so severely impact on the economy and indeed on the very thing Labour's trying to put right, business confidence.

Lange used to say he knew little about economics, that's why he had Roger Douglas by his side which of course came to an end when his Finance Minister wasn't invited for a cup of tea. Helen Clark used to leave most of the economic talk to Michael Cullen but the following two National Prime Ministers, John Key and Bill English, had a firm hand on the tiller and were well equipped to wax lyrical on money matters.

So perhaps in the future, Ardern should listen more carefully or better still, in the future leave her ministers to do the talking about the minutiae of money to avoid the sounder of swine in the parliamentary trough.

And no, she doesn't believe pigs can fly.