tag:blogger.com,1999:blog-4052593945054595675.post7904492958492604164..comments2024-03-28T14:16:10.498+11:00Comments on Dr Kevin Bonham: Poll Roundup and Seat Betting Watch: Scruff Of The Neck Edition (August 13)Kevin Bonhamhttp://www.blogger.com/profile/06845545257440242894noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-4052593945054595675.post-56145519126145399012013-08-16T11:46:46.923+10:002013-08-16T11:46:46.923+10:00"Either the markets are justifiably confident..."Either the markets are justifiably confident that Labor should not now recover or else what we are seeing is a fully-fledged run in which the prices are affected by belief that the prices themselves are predictive."<br /><br />Heh, nails it. <br /><br />Well, maybe not in this particular case... I see very little evidence the ALP is in the game at present--my personal view is that they'll only form government again on the back of a black swan--but I am certain people place way too much stock in predictive accuracy of political betting markets.mikhfhttps://www.blogger.com/profile/01270827523976317291noreply@blogger.comtag:blogger.com,1999:blog-4052593945054595675.post-39262082812773200842013-08-13T21:01:05.200+10:002013-08-13T21:01:05.200+10:00There's not much of a pattern when looking at ...There's not much of a pattern when looking at the predictive errors of what I take to be the final federal Newspolls (based on their website listings) over time: -2.2, -3.1, +1.9, -0.1, -2, +2, -2.7, +0.7, -0.1. (Error is in 2PP prediction of Coalition vote share).<br /><br />The Bludgertrack method is stated here: http://blogs.crikey.com.au/pollbludger/bludgertrack-2013-methodology/ BT uses multiple elections for Newspoll and Galaxy (including state elections, which might be contentious) and then does the "bias" adjustment for the rest on their behaviour relative to the rest of the aggregate. I'm a bit more comfortable with this than either using just the last election or assuming zero-sum across all pollsters, so at a particular point I swiped William's primary loadings for some of the pollsters and translated them to 2PP as I don't have historic data sets for all pollsters. At the moment, BT doesn't have its current loadings up. Kevin Bonhamhttps://www.blogger.com/profile/06845545257440242894noreply@blogger.comtag:blogger.com,1999:blog-4052593945054595675.post-43737366975819929312013-08-13T19:58:04.445+10:002013-08-13T19:58:04.445+10:00Betting market result is interesting. If you assum...Betting market result is interesting. If you assume that Labor will win 63 seats, and solve the cube rule (s/[1-s]=[v/1-v]^3), it suggests a Labor TPP vote around 47.3 per cent. <br /><br />If Labor won 65 seats, the cube rule prediction would be a TPP of 47.8 per cent for Labor.<br /><br />Link: http://marktheballot.blogspot.com.au/2012/11/cube-law.htmlMark Graphhttps://www.blogger.com/profile/10462713733051104779noreply@blogger.comtag:blogger.com,1999:blog-4052593945054595675.post-90890036924540530192013-08-13T19:47:34.252+10:002013-08-13T19:47:34.252+10:00Yep, I had that wrong (not sure how since it's...Yep, I had that wrong (not sure how since it's obvious how it works in other sports); I've removed that bit. Ta.Kevin Bonhamhttps://www.blogger.com/profile/06845545257440242894noreply@blogger.comtag:blogger.com,1999:blog-4052593945054595675.post-70581943081354233922013-08-13T19:44:01.730+10:002013-08-13T19:44:01.730+10:00The question of how you calibrate the pollster bia...The question of how you calibrate the pollster bias is pretty interesting, of course. Jackman's model calibrates off the last election, as does mine. <br /><br />As you have pointed out, you can use a series of past elections to do this. This is fine provided that you think the methodology hasn't changed over that period. How far back are you willing to go to make that assumption? Consider the massive uptake of smartphones (and mobiles more generally), such that a lot of people no longer have a landline.<br /><br />I'd probably be happy to use the 2010 and 2007 elections as part of the calibration, but I'd be pretty cautious about going further back than that.<br /><br />Another way of looking at this is to plot the post-hoc bias of eg Newpoll against time, and to see whether this quantity is random (as you'd expect). Small sample size will be a hindrance in telling you anything, particularly if they keep changing their methodology (as you'd expect them to do).<br /><br />In a world where pollsters constantly change their methodology, using the last election only may be the safest option, although not necessary the most unbiased one.Julian Kinghttps://www.blogger.com/profile/09999443797525672413noreply@blogger.comtag:blogger.com,1999:blog-4052593945054595675.post-65269659978296205262013-08-13T19:16:10.932+10:002013-08-13T19:16:10.932+10:00"Also the seat handicap market thinks Coaliti..."Also the seat handicap market thinks Coalition -10.5 will defeat Labor +10.5, implying that that market expects a seat difference exceeding 21"<br /><br />Are you sure that this is how to interpret the handicap markets? (I think you've got it wrong, but now I'm second-guessing myself!) My understanding is that it's Coalition-10.5 v Labor, or Coalition v Labor+10.5. In other words, "Will the Coalition win at least 10.5 seats more than Labor, or won't they?" The 0.5 is added to the line to ensure that there can't be a tie.<br /><br />It looks like Sportsbet are moving their line to keep the odds even, which is a useful market to have: currently they're giving the Coalition a 14.5 seat lead.David Barryhttps://www.blogger.com/profile/08378763233797445502noreply@blogger.com