My question is to the Prime Minister, and I refer her to her statement before the election that there will be:

… no carbon tax under the government I lead,

and her statement after the election that a carbon tax is:

… the most economically efficient way of dealing with carbon pollution.

Yet this week the Secretary of the Department of Climate Change and Energy Efficiency told the Senate that since 2008:

We have not conducted full economy-wide modelling of the carbon price.

I ask the Prime Minister: how can she responsibly claim that a carbon price is economically efficient if there has not been any new economic modelling for the past three years?