Here is a comparison of election predictions by various outlets of this past election. The top part of the table only shows prediction results for only the single district seats and the bottom part of the table includes the proportional representation seats.
The prediction outlets are composed of internet portals kuchikomi (クチコミ＠総選挙) and shuugi.in (総選挙予測市場サイトshuugi.in), newspapers (Asahi), magazines (Asahi, Mainichi and Post) and TV (TBS, Fuji, Asahi, Tokyo, and Nihon).
So we see a general trend of overestimating the number of seats for the DPJ and underestimating for the LDP. It is so consistent across these media outlets (except for the magazines), it is worth looking into. As far as I know, only the kuchikomi people have posted data on their election results, I will be analyzing the data in a future post.
BTW, most of these outlets do not get accurate predictions according to a chi-squared test. The Asahi outlets seem to do well, but shuugi.in is just amazing. They basically got the results exactly right except for a little overestimation of the DPJ results. This may be due to them giving away some candidates due to overflow and those things are hard to predict.
I believe the methods used for shuugi.in uses prediction markets that lets users buy “stocks” to bet candidates that they think are going to win the election. I haven’t studied the method in detail, but I will do that once I get the time. The other internet prediction site, Kuchikomi, uses kuchikomi (口コミ), which basically means internet chatter. Again, I’m not sure what their exact methods are, but it is different from analyzing internet polling.
As for the other media outlets, I am guessing they used traditional opinoin polls. They did perform better than Kuchikomi’s predictions, but not nearly good enough compared to shuugi.in.
Brilliant. Discovered your blog through Japan Probe. Your blog is everything Our Man wishes he could be.
[...] Prediction Analyses 2009 Japan Lower House Elections As promised in a prior post, I’ve finished the data entry for the Kuchikomi (クチコミ総選挙) election predictions. [...]
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