An election-forecasting tool based at the University of Iowa that’s more accurate than many national polls p a “dead heat” in the presidential race. Tom Rietz is co-director of the Iowa Electronic Markets.Rietz, a U-of-I finance professor, says democrat Al Gore has pulled slightly ahead of republican George W-Bush, but Gore’s lead is still well inside the margin of error. Rietz says the electronic markets are based, not on pork bellies or May wheat, but on political candidates. The I-E-M has seven thousand traders and more than 200-thousand dollars in equity. Trades can be made for as little as five-dollars or as much as 500. Rietz says the I-E-M has traditionally been a very accurate forecaster for presidential elections.During the 1988, ’92 and ’96 presidential races, the average margin of error has only been about 1-point-2 percent. Registered I-E-M traders can continue trading in presidential candidates’ shares through tomorrow, but new traders are no longer being accepted for that market.