jipkin’s PredictIt Preview – Week of 10/22/2018

Just over two weeks to go!

Midterm spreadsheet | Other midterm resources

If you haven’t yet, it’s time to start getting your preparations in order for the big night.  I’ll have some content for you later this week with some thoughts for what things to watch for to get as early a jump as possible on which way things are breaking.

In the meantime, I’ve updated The Spreadsheet to include several more models on the House and Senate page (538 lite and deluxe and all three for governors, Noah Rudnick’s fundamentals model, and Harry Enten’s CNN models).  With these new data, we have enough to calculate a ‘model consensus’ for each individual race.  For instance, the Senate races look like this:

AZ mispriced.png
To get the ‘model consensus’ I discard the highest and lowest modeled win probabilities and then average the rest.  Then I calculate how different the PredictIt price is from that consensus.

The story here is largely the same as I noted (with fewer data) in my Markets vs Models blog post.  Many individual Senate races are over 15c red-shifted (priced more favorably for Republicans) compared to what the model consensus says.  There are several possible reasons for this.  It could be that these markets are much more sensitive to recency, and are more highly weighting new polls rather than a fuller look including old polls.  It could be that the low-information bettors that tend to be conservative-leaning are more comfortable with these Senate races where they feel like they can sink their teeth into each candidate.  It could be left-over inertia from the Kavanaugh bump with the market correcting only very slowly because of people penny-flipping shares.  Or it could be that PredictIt bettors are just on to something in the Senate!  We will get lots more polling this week (including a rather eye-opening one from CNN in Florida today) and we’ll see if/how markets correct in response.

The Kavanaugh Bump fades

Did you feel it?  Some time around last Tuesday/Wednesday, Democrats started performing better again in district-level polling.  Patrick Ruffini, who’s been modeling this based on the NYT microdata, also notes the shift.  We’re definitely not back at early September numbers for the Dems, but it’s a marked improvement since Kavanaugh reminded Republicans about voting.  In the end, the story I suspect will be as its been for all the primaries and special elections since Trump was elected: Dems are fired up and they’re going to vote in big numbers.  The only question is how many Rs join them.

As always, keep an eye on the NYT polls to see how the winds are blowing.


(New to tweet markets?  Read my guides starting here.)


Last week I said that B7 in RDT really wanted to win but would ultimately be denied the rose… and I was wrong!  To my credit, it did die all the way to single digits before an epic Tuesday brought it back to life.  We’re in a quasi-similar spot this week.  Again B7 wants to win.  Again it feels like the tweets might not be there.  Will Donny again rescue it?

PT/WHT and VPT are pricing in a quiet campaign-related week at the moment, with B1 taking comfortable leads in WHT and VPT.  I’ll root for something like last Wednesday’s massacre to happen in WHT but I don’t really expect it.  Pence is known for finding ways to tweet when you don’t expect him to… but he’s starting in a deep hole here.  As for Scavino’s Funhouse of Pain?  In the short term things look good for B1.  But one must always tread cautiously there.


(New to polling markets?  Read my guides starting here.)

538 TA | 538 Ballot | RCP TA Weekly | RCP TA Monthly

Aside from individual race and Senate polls (hoping for another brace of NBC/Marists this week), it should be an interesting one in the polling markets.  We just got a nice NBC that might spike spiked 538 TA (and has implications for RCP and RCP October).  Fox and CBS just came but I think the usual weeklies will give us enough action anyway.

Brazil Run-Off

Winner | Margin of Victory| Winner vote share over 60%?

Hey this is a thing that’s happening next Sunday!  My limited understanding is that Bolsonaro is an asshole and he’s going to win and that’s about all I know.  Here’s the wiki on it if you want a brief overview.  I’ll do a preview for it later in the week after I do a bit more research.


Disclaimer: I probably have positions or intend to take positions in just about all the markets I discuss herein.  You should always do your own research prior to making any investment decision. You should consider my advice and knowledge I share to be fundamentally biased in its presentation and selection by my own financial incentives.  While I do not knowingly lie I certainly do knowingly omit information that I think gives me an edge.

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