Wednesday, October 31, 2012

The Turnover Index - Week 9

Here are the Turnover Index numbers for Week 9 of the NFL season.  The purpose of these weekly posts is to find betting opportunities by exploiting the market's tendency to overvalue a team's season to date defensive turnovers when evaluating future performance.  See here and here for more background.

Last week's picks went 1-1 against the spread.  Carolina covered the 7.5 point spread in their game against the Bears.  The Cowboys, as a 2.5 point underdog, were unable to cover the spread, done in by Dez Bryant's pinky (and instinct for self preservation).

Sunday, October 28, 2012

College Football Rankings - Now Updated Daily

Over the past few weeks, I had taken several stabs at creating a betting market power ranking for College Football.  Now that I've got the methodology ironed out and the code automated, I'm launching a daily version of the rankings.  These will update every morning with the latest lines and over/unders.  The format is very similar to the format I've established for my NFL rankings.

Here is an overview of the table (you can also hover over the column headings in the table for a brief description):

Wednesday, October 24, 2012

The Turnover Index - Week 8

Here are the Turnover Index numbers for Week 8 of the NFL season.  The purpose of these weekly posts is to find betting opportunities by exploiting the market's tendency to overvalue a team's season to date defensive turnovers when evaluating future performance.  See here and here for more background.

The Turnover Index went 2-0 against the spread last week, although the Bears-Lions game was about as close as you can get (the point spread was 6.5 points, which the Lions just covered by closing the gap to 6 points with 36 seconds left in the game). The other pick, the Colts, beat the Browns by 4, having been favored by 2.5.

Saturday, October 20, 2012

NFL Rankings - Strength of Schedule

At the risk of turning my daily NFL rankings into a cluttered, confusing mess, I have added a couple new columns.

Strength of Schedule

The rankings table now shows a set of columns labelled "SOS", which stands for Strength of Schedule.  This is a very simple calculation where I take each team and calculate the average GPF (Generic Points Favored) of their opponents, split by games already played (the "Past" column) and by remaining games (the "Future" column).  The numbers shown are in terms of GPF, with the corresponding rank beside it.

College Football Rankings - Week 8 Update

As I mentioned in the comments of my week 8 college football rankings post, the rankings looked a bit out of whack.  I've tinkered with things a bit more and I now think that I've got an approach that I can stick with week to week.  Here is a rundown of the methodology (or you can skip to the bottom for the rankings):

Wednesday, October 17, 2012

College Football Rankings - Week 8

Here are the betting market rankings for College Football for week 8.  See my first post for background and my Methodology page for a simple example of how the rankings work.

For this version, I have added the offensive and defensive components of each team's ranking (oGPF and dGPF).  I can derive these by looking at the over/under in combination with the point spread.

Monday, October 15, 2012

The Turnover Index - Week 7

San Diego and Denver have yet to play, but they are both on bye next week, so I can go ahead and update the Turnover Index with data through week 6.  If you don't know what this is, see here and here.

Things evened up this week on the season-to-date results, with the Turnover Index predicting Oakland to cover the nine point spread against Atlanta (which they did, in a wild, losing effort).

NFL Rankings - Projected Wins

"IT'S A SIMULATION!"
There is a new feature added to my daily NFL team rankings. Building off of a suggestion from commenter Ben Moore on my MLB rankings, there is now a column labeled "Projected Wins". With each day's rankings, I also simulate the remainder of the regular season (10,000 times) and display the following:

  • Average Projected Wins - This is the average projected regular season wins, based on my 10,000 simulation runs.  This only simulates future games (wins in-hand are taken as a given).
  • Projected Win Ranking - How that team's projected wins compares to the rest of the league
  • Projected Win Distribution - On the far right is a bar graph displaying the team's projected win distribution, once again summarized from my 10,000 run simulation. The scale is identical for each team, with the x-axis varying from 0 wins to 16 wins for each team.  This can be viewed as an application of Edward Tufte's concept of small multiples.
I simulate the season as follows:

Saturday, October 13, 2012

College Football Rankings - Week 7 Update

My first post on college football rankings was calculated prior to the release of the betting lines for this week's games.  See below for an updated version that reflects the latest lines (LSU dropped and South Carolina shot up to reflect the fact that the Tigers are only a 2.5 point favorite at home over the Gamecocks.

The Turnover Index - Week 6

The Turnover Index got off to a rough start this season.  The first and only pick was for Jacksonville to cover the spread as a 6 point underdog against Chicago.  Just missed it.

Turnover Index Through Week 5 (ATS): 0-1-0

Here is the outlook for the week 6 games (see here and here for background):


"home.dto" and "away.dto" are the season-to-date defensive turnovers for the home and away teams. As before, we're looking for any games where there is at least a 10 turnover differential between the teams. The only game that qualifies this week is Oakland at Atlanta. Oakland has 11 fewer turnovers, so the expectation is that Oakland is more likely than not to cover the 9 point spread.

Sunday, October 7, 2012

College Football Rankings - Week 7

The 1892 Alabama Football Team
When men were men and hats were hats
Here is my first attempt at creating a betting market power ranking for College Football.  The goal here is to try to reverse engineer an implied power ranking from the point spreads set by Vegas and the offshore sportsbooks.  In a nutshell, I'm trying to figure out what the betting public "thinks".  See my Methodology page for a simple example of how the rankings work (also see here for a detailed NFL example).

Here are some details on the methodology:
  • Home field advantage is assumed to be worth 3.5 points (I derived this from 5 seasons worth of point spreads)
  • Recent games are weighted more than games played early in the season.  The weight used is as follows: weight = 1/(2.8 + days), where days is how many days ago the game in question was.
  • The key output is GPF, which stands for Generic Points Favored.  It's what you would expect the team to be favored by against a Division 1A average opponent at a neutral site.

Wednesday, October 3, 2012

The Turnover Index - Week 5

One of my first posts on this blog was on the topic of NFL Turnover Differential and the Point Spread. In that post, I found that teams with fewer season-to-date defensive turnovers than their opponent tended to cover the spread more often than not.  The presumed reason for this is that:

  1. Turnovers are more random than the betting public realizes, and so the point spread "overcorrects" for prior game turnover performance.
  2. To the extent that turnovers are not random, they are more a function of the offense.  Interceptions are more "thrown" than caught and fumbles are more "lost" than forced.