Matter of Stats

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2015 - Team Ratings After Round 17

This week, 10 teams in four clusters changed Ranks on ChiPS:

  • The Roos climbed two places into 5th, pushing the Pies and the Swans both down by one place into 6th and 7th respectively
  • Port Adelaide slipped two places into 11th, allowing the Cats and the Dogs to climb by a spot each into 9th and 10th respectively
  • St Kilda leapfrogged Essendon, taking 13th and relegating the Dons to 14th
  • Gold Coast leapfrogged Carlton, taking 16th and relegating the Blues to 17th

Hawthorn registered the round's biggest Ratings Point (RP) transfer, snatching 6.8 RPs from Carlton to lift its Rating over 1,050 for the first time this season and establishing almost a three-goal equivalent RP gap over the rest of the competition. The two other big gainers this week were the Roos (+4.6 RP) and the Saints (+3.3 RPs).

ChiPS now has the teams falling naturally into four groups:

  • Significantly Above Average: Rated 1,030+ : Hawthorn and West Coast
  • Above Average: Rated 1,010 - 1,020 : Richmond, Fremantle, Kangaroos, Collingwood, Sydney
  • Below Average: Rated 990 - 1,000 : Adelaide, Geelong, Western Bulldogs, Port Adelaide, GWS, St Kilda, Essendon
  • Significantly Below Average: Rated 965 - 980 : Melbourne, Gold Coast, Carlton, Brisbane Lions

(For those of you who would still like to see the full detail version of this table, it's available at the end of this post. Click on it to access a larger version.)

MARS re-Ranked seven teams, most notably elevating the Roos two places into 6th, dropping the Pies two places into 7th, and also dropping Melbourne two places into 17th. It would group the teams similarly to ChiPS, but elevate Geelong, Adelaide and Port Adelaide into the "Above Average" group.

Only two teams are now Ranked more than two places differently by ChiPS and MARS:

  • Sydney, Ranked 7th by ChiPS and 4th by MARS
  • Port Adelaide, Ranked 11th by ChiPS and 8th by MARS

The rank correlation between ChiPS' and MARS' Team Rankings now stands at +0.963, and between their Team Ratings +0.964.

COLLEY, MASSEY AND ODM

Massey was the System making fewest Ranking changes this week, altering the position of just four teams, none of them by more than a single place. Colley re-Ranked only one team more, but it did make one multiple-place move, dropping GWS from 8th to 10th. ODM re-Ranked seven teams, including elevating the Cats two places into 10th, dropping GWS three places into 12th and elevating the Roos three places into 8th.

At the end of it all, Massey and ODM sport almost identical Team Rankings, the correlation between them now +0.996, and no pair of Systems has Team Rankings whose correlation is below +0.917 (the result for both the pairings of MARS and Colley, and ChiPS and Colley).

In terms of congruence with the competition ladder, Colley, as usual, sets the high-water mark at +0.994, while MARS finds itself most distant - but not all that far away - at +0.905.

ODM OFFENSIVE AND DEFENSIVE COMPONENTS

The stability of ODM's Team Defensive Rankings continues this week, with just the one swap of positions in the Top 5:

  1. Fremantle (no change)
  2. West Coast (no change)
  3. Hawthorn (up 1 spot)
  4. Sydney (down 1 spot)
  5. Richmond (no change)

Positions 6, 7 and 8 remained unchanged as well, occupied by Collingwood, the Western Bulldogs, and GWS respectively.

Offensive Team Rankings were even more stable, there being no changes at all in the Top 5, which remains:

  1. Hawthorn
  2. West Coast
  3. Adelaide
  4. Kangaroos
  5. Collingwood

Just below this group, Port Adelaide now lies 6th, the Western Bulldogs 7th, and Geelong 8th.

MoSSBOD agrees with ODM's Top 5 Defensive Teams, though has them in a different order, and ranks only one team on Defence more than three places differently to ODM: St Kilda, which MoSSBOD Ranks 10th and ODM Ranks 15th.

On Offence, MoSSBOD still feels that the Tigers are a top 3 team while ODM Ranks them 10th, and MoSSBOD has Port Adelaide Ranked 12th on Offence to ODM's 6th. Three other teams, Fremantle, Sydney and St Kilda, are Ranked four places differently by the two Systems.

The small number and generally small size of the Ranking differences discussed above are reflected in the relevant rank correlations, which are:

  • between Defensive Rankings is +0.942
  • between Offensive Rankings +0.845
  • between Combined Rankings +0.961.

I note in passing that the MoSSBOD data above reveals Hawthorn's Offence to be more than 2 scoring shots (or about a goal and a quarter) better than any other team in the competition. As well, West Coast's Defence is a little over a scoring shot better than any other team.

PREDICTIVE ACCURACY

MARS finally managed to out-tip ChiPS this week and has now taken a one tip lead as a result. Relative to the other Systems, MARS:

  • leads Colley by 19 tips (no change)
  • leads Massey by 12 tips (down 1)
  • leads ODM by 11 tips (down 1)
  • leads the ODM Offence Ratings by 7 tips (no change)
  • leads the ODM Defence Ratings by 17 tips (down 2)

CHIPS AND MARS - FULL TABLE