Five questions about the Treasury model
Where is it?
This report has now appeared in almost every major media outlet before it has even been published. Why?
What if the government economists made a mistake in their calculations, like they did with the projected costs of the West Coast Mainline? None of this has been seen by any independent body outside the government as far as we know.
Who wins, who loses?
The headlines say we'll be £4,300 worse off a year per household on average. This sounds straightforward, but , this is nothing like saying that every household will be £4,300.
Not everyone will be affected in exactly the same way. There will be winners and losers. Who will they be?
What's going to happen with immigration?
This morning the Chancellor said the figures are based on population forecasts by the Office for National Statistics.
There are two problems with that. First, the ONS numbers assume both that we remain in the EU and that we continue to have higher immigration than the government’s target. Secondly, one big reason for many people to support leaving the EU is to get more control over immigration.
How sure are you really?
Crystal balls are always hazy, which is why economic ones should say what the best and worst likely scenario is.
At best, economic models should describe what we can reasonably expect, if you start from a given starting point, and start with some chosen assumptions. Then they need to say how much changing those assumptions or other effects might change the final result.
None of that was published last night, or even this morning.
These headlines are based on trying to get something like Canada's trade agreement, which the Chancellor made clear this morning he is not keen on. The Canada model has been advocated by at least the Mayor of London, although he later changed his mind.
So what does the government think is the best deal they could get? How much better or worse off might we be then?
Where are the data and the calculations?
Pages of text are fine—when they are eventually published—but at heart, an economic model is numbers and calculations.
The government needs to publish the data and calculations it used so that others can reproduce them and test them, and try out the effects of different assumptions too.