quarta-feira, janeiro 09, 2008

E o outro fiasco...(actualizado)

Bad Bet: Why were the political futures markets so wrong about Obama and Clinton?
By Daniel Gross

"So, I've been watching the action in one of the political futures markets this evening, Intrade. And the action in this prediction market has reinforced my opinion that these are less futures markets than immediate-past markets. The price movement tends to respond to conventional wisdom and polling data; it doesn't lead them. Throughout the day and into the early evening, while polls were still open, Democratic investors, mimicking the post-Iowa c.w. and polls, believed Obama was highly likely to be the Democratic nominee. The Obama contract was trading in the lows 70s, meaning investors believed he had a 70 percent chance of being the nominee, while Hillary Clinton contracts were in the 20s. But between 7 p.m. and 8 p.m., as the Concord Monitor began to post early returns showing Hillary Clinton in the lead, the contracts started to move quickly."

Nobody knows anything
By Paul Krugman
"But to be more specific, the prediction markets — which you see, again and again, touted as having some mystical power to aggregate information, know no more than the conventional wisdom. (...) From inevitability to pitiful failure to front-runner again in just a few days. There’s no hint that the market saw either Iowa or New Hampshire coming, or knew anything beyond the bloviations of the talking heads."

E um paper de Setembro de 2007:
Are Political Markets Really Superior to Polls as Election Predictors?
ByRobert Erikson and Christopher Wlezien
"By our tests, the IEM election markets are not better than trial-heat polls for predicting elections. In fact, by a reasonable as opposed to naïve reading of the polls, the polls dominate the markets as an election forecaster. This is true in the sense that a trader in the market can readily profit by 'buying' candidates who, according to informed readings of the polls, are undervalued. Moreover, we find that market prices contain little information of value for forecasting beyond the information already available in the polls."
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