One of the things any reputable business school teaches its students is economic forecasting, the method of calculating financial losses or benefits that might accrue as a result of an event, policy or legislation. Somehow the folks at the Regional Chamber and Growth Association seem to have no clue about how to do it. When the Rams made it to the Super Bowl last year, the RCGA calculated that the value of the "exposure" time for St. Louis was $344 million. They tallied the actual mentions of St. Louis on- or offscreen and the number of times the words "St. Louis" appeared onscreen. It added up to 86 minutes. So they multiplied that figure by the airtime rate during the game -- $2 million for a 30-second spot -- and came up with $344 million. Late last year, when the city was debating an ordinance to exempt stock-option income from the earnings tax, the RCGA said the city would lose only about $350,000 a year. They based it on a "survey" of five large local companies, which told them they (and their executives) had paid $120,000 a year in the past three years. They multiplied that figure by three (and subtracted $10,000 for no apparent reason) and came up with $350,000 as the figure for all of the hundreds of city companies and their executives. Funny thing is, no one blinked. Not Mayor Francis Slay, who pushed the exemption bill, not Ald. Lyda Krewson (D-28th), who sponsored the bill, and not the Post-Dispatch, which repeatedly reported the figure. The bill passed. The city will begin to lose the money in the coming year. Someone send these RCGA guys back to school before they bury the city they aim to save.