The baseball nerd who used his genius for statistics to make startlingly accurate predictions in the 2008 US presidential race has weighed into the British election – and his conclusions make chilling reading for Labour.

Nate Silver, who correctly predicted the result between Barack Obama and John McCain in 49 out of America's 50 states, argues that the most popular method for translating opinion poll results into numbers of seats in parliament greatly overstates how well Labour will perform, giving the false impression that the party "has a fairly large buffer zone before facing total Armageddon".

The concept of uniform swing assumes that the projected national swing to or away from any given party will be manifested in identical vote swings in every constituency. If an opinion poll suggests that the Conservatives are up six points on 2005, for example, the assumption is that they will do six points better in each constituency. The method has long been criticised as flawed, especially in elections with strong third parties. But on his blog FiveThirtyEight.com, Silver goes one step further, presenting his own alternative methodology that suggests a disastrous May 6 performance for Labour.

Silver's method breaks up the monolithic uniform swing and instead assigns specific percentages of the parties' votes in 2005 to other parties in 2010. Using a recent polling average of the three main parties – with the Conservatives on 34%, the Lib Dems on 29.1%, and Labour on 26.9% – the differences between the two methods become stark. Using uniform swing, those percentages translate into 253 Labour MPs, 271 Conservatives, and 93 Lib Dems. Using Silver's method, Labour ends up with just 214, with the Conservatives surging to 304, and the Lib Dems on 101.

Another scenario considers what would happen if 10% of those who voted Labour in 2005 switched to the Conservatives and 15% to the Lib Dems, while 10% of 2005 Tory voters also switched to the Lib Dems. Under uniform swing, Labour would have 254 seats, nearly neck-and-neck with the Tories on 256. Silver's method gives the Conservatives 276 to Labour's 218.

Last year, Time magazine named Silver one of the world's 100 most influential people for the accuracy and impact of his presidential predictions. The Labour party may will be hoping that he has lost his touch.