TY - JOUR AU - Wolfers,Justin AU - Zitzewitz,Eric TI - Prediction Markets JF - National Bureau of Economic Research Working Paper Series VL - No. 10504 PY - 2004 Y2 - May 2004 UR - http://www.nber.org/papers/w10504 L1 - http://www.nber.org/papers/w10504.pdf N1 - Author contact info: Justin Wolfers Department of Economics University of Michigan 611 Tappan St Lorch Hall #319 Ann Arbor, MI 48104 Tel: 734-764-2447 E-Mail: jwolfers@umich.edu Eric Zitzewitz Department of Economics Dartmouth College 6106 Rockefeller Hall Hanover, NH 03755 Tel: 603/646-2891 Fax: 603/646-2122 E-Mail: eric.zitzewitz@dartmouth.edu M2 - featured in NBER digest on 2004-11-01 AB - We analyze the extent to which simple markets can be used to aggregate disperse information into efficient forecasts of uncertain future events. Drawing together data from a range of prediction contexts, we show that market-generated forecasts are typically fairly accurate, and that they outperform most moderately sophisticated benchmarks. Carefully designed contracts can yield insight into the market's expectations about probabilities, means and medians, and also uncertainty about these parameters. Moreover, conditional markets can effectively reveal the market's beliefs about regression coefficients, although we still have the usual problem of disentangling correlation from causation. We discuss a number of market design issues and highlight domains in which prediction markets are most likely to be useful. ER -