"That is brilliant." Learn the maths hack from @robeastaway that blew the minds of @ChrisMasonBBC and @TimHarford

Our same listener in Eastleigh also received this from Labour. It gives a different message to YouGov’s current MRP polling which puts Labour 10 points behind either the Lib Dems or the Conservatives in that seat... 10/13

Some use results from previous general elections. Opinions have shifted since then, and 90% of constituencies also have new boundaries. A listener in Eastleigh received this from the Lib Dems - the bars are also the wrong height to reflect their previous performance. 8/13

This is from a Lib Dem leaflet in Central Devon It makes no mention of the Conservatives who have held the seat since it was created. The Lib Dem vote share is from 2010 - But they’ve come third or fourth in the last three general elections there. Labour’s is from 2017. 6/13

But the Conservatives chose to use the figure including additional childcare AND presumed it would be used by 50% of pupils - that would cost up to £1.5bn a year. 10/11

For Labour’s pledge to introduce ‘universal breakfast clubs' for primary schools in England, the Treasury gave two models. One covered food costs and staff time to prepare food. The second added 1 hour of free childcare. With a 30% take up, the first would cost ~£200m a year 9/11

Political special advisors also placed assumptions in the Treasury calculations. Looking at insourcing again… In the Treasury analysis, advisers wanted it to be assumed that services would be 7.5% less efficient if brought under greater government control. 8/11

But there are questions about how the Conservatives chose some figures. With Labour’s pledge to take back control of more public services, the Conservatives assumed 50% of contracts renewed annually would be insourced, costing £6.4bn - the highest % in the Treasury numbers. 7/11

The Conservatives added up what they think Labour would spend & raise. But several policies including continued support for Ukraine, the Green Prosperity Plan and Fair Agreement for Social Care were not analysed by the Treasury. Together these make up around 40% of the £££ 5/11

We were asked to investigate this claim made recently during a discussion about HS2. Is it true? Here's a More or Less thread (1/9)