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RE: [APBR_analysis] Re: Team Ratings (adjusted for schedule strength)

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  • Michael Tamada
    I was thinking of a simpler, cruder home-away correction. Although some teams seem to thrive at home and wilt away from it (Utah) and others seem to be road
    Message 1 of 18 , Jan 5, 2004
      I was thinking of a simpler, cruder home-away correction. Although
      some teams seem to thrive at home and wilt away from it (Utah) and
      others seem to be road warriors as good on the road as at home (Boston,
      Seattle), I was thinking in terms of simply giving a single universal
      home-away correction that would be applied to every home team's offense
      rating or defense rating (or both, but I think this wouldn't really matter,
      because it'd simply be a constant to be added or subtracted).

      We would still need some home-away split data, but even if that's
      unavailable we could estimate what the home bonus should be: in
      most years, NBA teams win about 2/3 of their home games (I haven't
      looked at this year's data). Comparing a .667 team to a .500 team,
      how much better would its offense have to be to move it from .500
      to .667? (Or equivalently, how much better would its defense have
      to be?) Whatever that figure is, that's the home bonus to give
      to the home team's offensive rating (or defensive rating).

      Crude but simple and I think it would significantly help correct
      for teams which have had schedules which were either (a) unbalanced
      with respect to home and away games or (b) balanced with respect
      to home and away, but unbalanced in terms of having tough or easy
      road opponents, and vice-versa at home.


      --MKT


      -----Original Message-----
      From: ssims22000 [mailto:ssims2@...]
      Sent: Saturday, January 03, 2004 1:44 PM


      Hi,

      I haven't yet attempted to adjust for home vs. away. I know it
      would make a big difference for Portland - at the time of these
      ratings, the Blazers had played about twice as many home games as
      away games. By the end of the season, it should be a wash - most
      teams play each other teams 2 or 4 times, which means equal home and
      away games vs. those teams. In fact, the Western teams will have
      completely balanced schedules (2 games vs. each East team & 4 games
      vs. each West team). Now, though, there is significant imbalance.

      The only good way I can think of to handle this is to calculate
      home and away ratings for each team, and use these in the SoS
      calculations. I don't have access to that kind of breakdown (maybe
      Roland does).


      --- In APBR_analysis@yahoogroups.com, "Michael Tamada" <tamada@o...>
      wrote:
      > This is nice stuff, but do you also adjust for home vs away
      > games? I would guess that on average it's probably even
      > more important than opponent's strength in terms of helping
      > us to predict who's going to win a game.
      >
      > By the end of the season, teams will have all played half
      > their games at home and half away of course, so in that
      > sense the home-away thing becomes largely irrelevant at the
      > end of the season. But even then it may still have some
      > value, because teams don't play perfectly balanced home-and-
      > away schedules.
      >
      > --MKT
      >
      >





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    • Michael Tamada
      ... From: Michael Tamada Sent: Monday, January 05, 2004 9:44 AM ... Correcting myself, I think the appropriate comparison is a .667 team to a .333 team. That
      Message 2 of 18 , Jan 5, 2004
        -----Original Message-----
        From: Michael Tamada
        Sent: Monday, January 05, 2004 9:44 AM

        >most years, NBA teams win about 2/3 of their home games (I haven't
        >looked at this year's data). Comparing a .667 team to a .500 team,
        >how much better would its offense have to be to move it from .500
        >to .667? (Or equivalently, how much better would its defense have
        >to be?) Whatever that figure is, that's the home bonus to give
        >to the home team's offensive rating (or defensive rating).

        Correcting myself, I think the appropriate comparison is a .667
        team to a .333 team. That would give us the size of the bonus
        to give to the home team.


        --MKT
      • Dean LaVernge
        ... Here is the Home/Away records for the NBA (2004 Season through games of 1/4/2004) Home Road Season Wins Losses % Wins Losses %
        Message 3 of 18 , Jan 5, 2004
          On 5 Jan 2004 at 9:43, Michael Tamada wrote:

          >
          > I was thinking of a simpler, cruder home-away correction. Although
          > some teams seem to thrive at home and wilt away from it (Utah) and
          > others seem to be road warriors as good on the road as at home (Boston,
          > Seattle), I was thinking in terms of simply giving a single universal
          > home-away correction that would be applied to every home team's offense
          > rating or defense rating (or both, but I think this wouldn't really matter,
          > because it'd simply be a constant to be added or subtracted).
          >
          > We would still need some home-away split data, but even if that's
          > unavailable we could estimate what the home bonus should be: in
          > most years, NBA teams win about 2/3 of their home games (I haven't
          > looked at this year's data). Comparing a .667 team to a .500 team,
          > how much better would its offense have to be to move it from .500
          > to .667? (Or equivalently, how much better would its defense have
          > to be?) Whatever that figure is, that's the home bonus to give
          > to the home team's offensive rating (or defensive rating).
          >
          > Crude but simple and I think it would significantly help correct
          > for teams which have had schedules which were either (a) unbalanced
          > with respect to home and away games or (b) balanced with respect
          > to home and away, but unbalanced in terms of having tough or easy
          > road opponents, and vice-versa at home.
          >
          >
          > --MKT
          >

          Here is the Home/Away records for the NBA (2004 Season through games of 1/4/2004)

          Home Road
          Season Wins Losses % Wins Losses %
          1947 202 129 0.610 129 202 0.390
          1948 107 85 0.557 85 107 0.443
          1949 212 132 0.616 132 212 0.384
          1950 351 167 0.678 167 351 0.322
          1951 254 85 0.749 85 254 0.251
          1952 213 80 0.727 80 213 0.273
          1953 195 83 0.701 83 195 0.299
          1954 151 84 0.643 84 151 0.357
          1955 139 59 0.702 59 139 0.298
          1956 141 80 0.638 80 141 0.362
          1957 172 76 0.694 76 172 0.306
          1958 150 85 0.638 85 150 0.362
          1959 148 80 0.649 80 148 0.351
          1960 149 84 0.639 84 149 0.361
          1961 156 85 0.647 85 156 0.353
          1962 166 107 0.608 107 166 0.392
          1963 184 109 0.628 109 184 0.372
          1964 185 126 0.595 126 185 0.405
          1965 178 125 0.587 125 178 0.413
          1966 197 89 0.689 89 197 0.311
          1967 193 128 0.601 128 193 0.399
          1968 241 182 0.570 182 241 0.430
          1969 315 206 0.605 206 315 0.395
          1970 312 207 0.601 207 313 0.398
          1971 402 262 0.605 262 402 0.395
          1972 385 277 0.582 277 385 0.418
          1973 393 268 0.595 268 393 0.405
          1974 410 262 0.610 262 410 0.390
          1975 472 266 0.640 266 472 0.360
          1976 484 254 0.656 354 484 0.422
          1977 634 268 0.703 293 609 0.325
          1978 610 292 0.676 292 610 0.324
          1979 600 302 0.665 302 600 0.335
          1980 588 314 0.652 314 588 0.348
          1981 586 357 0.621 357 586 0.379
          1982 565 378 0.599 378 565 0.401
          1983 585 358 0.620 358 585 0.380
          1984 640 303 0.679 303 640 0.321
          1985 601 342 0.637 342 601 0.363
          1986 617 326 0.654 326 617 0.346
          1987 627 316 0.665 316 627 0.335
          1988 640 303 0.679 303 640 0.321
          1989 694 331 0.677 331 694 0.323
          1990 713 394 0.644 394 713 0.356
          1991 730 377 0.659 377 730 0.341
          1992 689 408 0.628 408 699 0.369
          1993 676 431 0.611 431 676 0.389
          1994 677 430 0.612 430 677 0.388
          1995 661 446 0.597 446 661 0.403
          1996 718 471 0.604 471 718 0.396
          1997 684 505 0.575 505 684 0.425
          1998 708 481 0.595 481 708 0.405
          1999 452 273 0.623 273 452 0.377
          2000 726 463 0.611 452 737 0.380
          2001 711 478 0.598 478 711 0.402
          2002 703 486 0.591 480 709 0.404
          2003 747 442 0.628 442 747 0.372
          2004 297 179 0.624 179 297 0.376
          NBA 25136 14716 0.631 14824 25139 0.371

          DeanL
        • Michael Tamada
          Thanks, clearly my figure of 2/3 home wins was based on 1970s-1980s memories, in recent years the figure s been more like 3/5. There s a lot of little detailed
          Message 4 of 18 , Jan 6, 2004
            Thanks, clearly my figure of 2/3 home wins was based on 1970s-1980s
            memories, in recent years the figure's been more like 3/5.

            There's a lot of little detailed questions to be answered, such as
            which Home Win% figure to use, let's just pick this year's current
            value of 62%.

            Using ssims' ORate and DRate numbers, that corresponds to a team
            having approximately a 3.5 point advantage, in terms of ORate -
            DRate difference.

            So if a team has played 12 home games and 8 away games, it's got
            a 4-game imbalance, worth a cumulative 4*3.5 point ORate-DRate
            difference = 14, which spread over its 20 games is 0.7 points
            of ORate-DRate differential.

            So if the initial rating has the team appearing to be a .500
            team with ORate = 100 and DRate = 100, an estimate which
            corrects for its excessive home games would be ORate = 99.3
            (or, the .7 points could be split evenly between ORate and DRate).

            This is a crude measure of course;, if we had home-road splits
            of O and D, we could do separate corrections for ORate and DRate.

            And for theoretical correctness we should apply the same Home-
            Road correction to the Opponent's ratings, as well as the
            Opponents' Opponents' ratings.

            Better still would be to apply the correction to individual
            game scores, rather than each team's aggregate totals; and
            to base the ratings on the outcomes of the individual games
            rather than the aggregate season totals; and to permit
            individual teams to have differing home bonuses instead of
            assigning all teams a 3.5 home bonus; and to solve the
            simultaneous equations for looking at opponents'
            opponents' opponents' ... ad infinitum; and etc. etc.

            But those procedures would require a lot more data and a lot
            more work. This crude home-road correction is simple and
            I would guess cleans up a good chunk of the home-road bias.



            --MKT




            -----Original Message-----
            From: Dean LaVernge [mailto:deanlav@...]
            Sent: Monday, January 05, 2004 8:24 PM
            To: APBR_analysis@yahoogroups.com
            Subject: RE: [APBR_analysis] Re: Team Ratings (adjusted for schedule
            strength)


            On 5 Jan 2004 at 9:43, Michael Tamada wrote:

            >
            > I was thinking of a simpler, cruder home-away correction. Although
            > some teams seem to thrive at home and wilt away from it (Utah) and
            > others seem to be road warriors as good on the road as at home (Boston,
            > Seattle), I was thinking in terms of simply giving a single universal
            > home-away correction that would be applied to every home team's offense
            > rating or defense rating (or both, but I think this wouldn't really matter,
            > because it'd simply be a constant to be added or subtracted).
            >
            > We would still need some home-away split data, but even if that's
            > unavailable we could estimate what the home bonus should be: in
            > most years, NBA teams win about 2/3 of their home games (I haven't
            > looked at this year's data). Comparing a .667 team to a .500 team,
            > how much better would its offense have to be to move it from .500
            > to .667? (Or equivalently, how much better would its defense have
            > to be?) Whatever that figure is, that's the home bonus to give
            > to the home team's offensive rating (or defensive rating).
            >
            > Crude but simple and I think it would significantly help correct
            > for teams which have had schedules which were either (a) unbalanced
            > with respect to home and away games or (b) balanced with respect
            > to home and away, but unbalanced in terms of having tough or easy
            > road opponents, and vice-versa at home.
            >
            >
            > --MKT
            >

            Here is the Home/Away records for the NBA (2004 Season through games of 1/4/2004)

            Home Road
            Season Wins Losses % Wins Losses %
            1947 202 129 0.610 129 202 0.390
            1948 107 85 0.557 85 107 0.443
            1949 212 132 0.616 132 212 0.384
            1950 351 167 0.678 167 351 0.322
            1951 254 85 0.749 85 254 0.251
            1952 213 80 0.727 80 213 0.273
            1953 195 83 0.701 83 195 0.299
            1954 151 84 0.643 84 151 0.357
            1955 139 59 0.702 59 139 0.298
            1956 141 80 0.638 80 141 0.362
            1957 172 76 0.694 76 172 0.306
            1958 150 85 0.638 85 150 0.362
            1959 148 80 0.649 80 148 0.351
            1960 149 84 0.639 84 149 0.361
            1961 156 85 0.647 85 156 0.353
            1962 166 107 0.608 107 166 0.392
            1963 184 109 0.628 109 184 0.372
            1964 185 126 0.595 126 185 0.405
            1965 178 125 0.587 125 178 0.413
            1966 197 89 0.689 89 197 0.311
            1967 193 128 0.601 128 193 0.399
            1968 241 182 0.570 182 241 0.430
            1969 315 206 0.605 206 315 0.395
            1970 312 207 0.601 207 313 0.398
            1971 402 262 0.605 262 402 0.395
            1972 385 277 0.582 277 385 0.418
            1973 393 268 0.595 268 393 0.405
            1974 410 262 0.610 262 410 0.390
            1975 472 266 0.640 266 472 0.360
            1976 484 254 0.656 354 484 0.422
            1977 634 268 0.703 293 609 0.325
            1978 610 292 0.676 292 610 0.324
            1979 600 302 0.665 302 600 0.335
            1980 588 314 0.652 314 588 0.348
            1981 586 357 0.621 357 586 0.379
            1982 565 378 0.599 378 565 0.401
            1983 585 358 0.620 358 585 0.380
            1984 640 303 0.679 303 640 0.321
            1985 601 342 0.637 342 601 0.363
            1986 617 326 0.654 326 617 0.346
            1987 627 316 0.665 316 627 0.335
            1988 640 303 0.679 303 640 0.321
            1989 694 331 0.677 331 694 0.323
            1990 713 394 0.644 394 713 0.356
            1991 730 377 0.659 377 730 0.341
            1992 689 408 0.628 408 699 0.369
            1993 676 431 0.611 431 676 0.389
            1994 677 430 0.612 430 677 0.388
            1995 661 446 0.597 446 661 0.403
            1996 718 471 0.604 471 718 0.396
            1997 684 505 0.575 505 684 0.425
            1998 708 481 0.595 481 708 0.405
            1999 452 273 0.623 273 452 0.377
            2000 726 463 0.611 452 737 0.380
            2001 711 478 0.598 478 711 0.402
            2002 703 486 0.591 480 709 0.404
            2003 747 442 0.628 442 747 0.372
            2004 297 179 0.624 179 297 0.376
            NBA 25136 14716 0.631 14824 25139 0.371

            DeanL






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          • ssims22000
            I did a few calculations of my own on a schedule strength modifier. ... I used .625 (or 5/8). Using the Pythagorean approximation, and assuming Offense = 1,
            Message 5 of 18 , Jan 8, 2004
              I did a few calculations of my own on a schedule strength
              modifier.

              --- In APBR_analysis@yahoogroups.com, "Michael Tamada" <tamada@o...>
              wrote:
              > There's a lot of little detailed questions to be answered, such as
              > which Home Win% figure to use, let's just pick this year's current
              > value of 62%.
              >
              I used .625 (or 5/8). Using the Pythagorean approximation, and
              assuming Offense = 1, then

              0.625 = (1 ^ EXP) / ( 1 ^ EXP + DEF ^ EXP)

              where EXP is the exponent you are using. I use 14, since it is
              about average for the last few seasons. Solving for DEF (the team
              defensive rating as a percentage):

              DEF = ( ( 1 / 0.625 ) - 1 ) ^ ( 1 / 14 )

              or DEF = 0.9641701. Balancing the defensive and offensive ratios
              around 100, I get Offense = 101.82417 and Defense = 98.20851.
              These are the expected offensive and defensive ratings for an
              average team at home. On the road, reverse the two. This gives a
              3.6 point difference, pretty close to what you found.

              > Using ssims' ORate and DRate numbers, that corresponds to a team
              > having approximately a 3.5 point advantage, in terms of ORate -
              > DRate difference.
              >
              > So if a team has played 12 home games and 8 away games, it's got
              > a 4-game imbalance, worth a cumulative 4*3.5 point ORate-DRate
              > difference = 14, which spread over its 20 games is 0.7 points
              > of ORate-DRate differential.
              >
              > So if the initial rating has the team appearing to be a .500
              > team with ORate = 100 and DRate = 100, an estimate which
              > corrects for its excessive home games would be ORate = 99.3
              > (or, the .7 points could be split evenly between ORate and DRate).
              >
              > This is a crude measure of course;, if we had home-road splits
              > of O and D, we could do separate corrections for ORate and DRate.
              >
              > And for theoretical correctness we should apply the same Home-
              > Road correction to the Opponent's ratings, as well as the
              > Opponents' Opponents' ratings.
              >

              What I will do when I have the time is change the weights in the
              formulas that calculate the schedule strength. Instead of each game
              being weighted as 1, a home game will weigh as .982 for offensive
              strength and 1.018 for defensive strength, and road games will weigh
              as the opposite.


              > Better still would be to apply the correction to individual
              > game scores, rather than each team's aggregate totals; and
              > to base the ratings on the outcomes of the individual games
              > rather than the aggregate season totals; and to permit
              > individual teams to have differing home bonuses instead of
              > assigning all teams a 3.5 home bonus; and to solve the
              > simultaneous equations for looking at opponents'
              > opponents' opponents' ... ad infinitum; and etc. etc.
              >
              > But those procedures would require a lot more data and a lot
              > more work. This crude home-road correction is simple and
              > I would guess cleans up a good chunk of the home-road bias.
              >
              >
              >
              > --MKT
              >
            • ssims22000
              The team ratings are updated through Jan. 27. I didn t have time to include a home/away modifier, so all ratings are calculated the same as before. ... with
              Message 6 of 18 , Jan 28, 2004
                The team ratings are updated through Jan. 27. I didn't have time
                to include a home/away modifier, so all ratings are calculated the
                same as before.

                --- In APBR_analysis@yahoogroups.com, "ssims22000" <ssims2@i...>
                wrote:
                > These ratings use a pythagorean approximation (exponent 14),
                with
                > offensive & defensive ratings adjusted as follows:
                >
                > ORate = Base ORate * Opp. Opp. ORate / Opp. DRate
                > DRate = Base DRate * Opp. Opp. DRate / Opp. ORate
                >
                > the ORates and DRates listed are adjusted to leage average = 100.
                > XWins is expected wins out of 82. Ratings are through Jan. 27.

                I've also included a Floor Rating (basically, team floor %
                adjusted for strength of schedule and league average. You can
                really tell the teams that rely heavily on the three (their floor
                ratings are much lower than their offensive ratings).


                Team ORate DRate XWins OFlR DFlR
                SAN 97.3 90.7 59.6 98.9 91.8
                SAC 108.1 101.0 59.3 105.9 102.0
                MIN 103.6 98.0 56.1 105.3 97.7
                LAL 102.8 98.1 54.2 104.8 98.4
                HOU 98.1 93.5 54.2 96.2 93.0
                IND 99.3 94.7 54.1 98.8 95.8
                DAL 108.9 103.9 54.1 107.3 102.9
                DET 99.5 95.3 53.2 100.4 96.0
                MEM 102.4 99.6 48.8 102.3 100.0
                DEN 100.7 98.3 47.8 101.5 99.6
                MIL 102.2 100.7 45.0 102.2 100.9
                NJN 96.7 95.4 44.8 97.1 95.0
                NOR 99.5 99.1 42.2 98.1 98.8
                UTA 101.4 101.6 40.6 104.1 101.1
                BOS 100.1 100.4 40.2 97.9 99.1
                SEA 104.1 105.1 38.3 99.9 104.0
                GSW 100.3 101.7 37.0 100.3 101.1
                LAC 102.3 103.8 36.9 102.9 104.4
                NYK 98.2 99.8 36.3 96.7 99.9
                PHI 97.3 99.3 35.4 97.9 98.4
                PHO 98.3 101.0 33.5 98.5 100.4
                POR 102.4 105.8 31.6 103.7 105.6
                CLE 97.5 100.8 31.5 99.7 100.2
                MIA 97.0 100.8 30.3 96.5 100.6
                TOR 93.9 98.1 28.7 93.3 99.8
                ORL 101.8 108.0 24.8 101.2 107.7
                WAS 94.5 100.9 23.6 95.5 100.8
                ATL 96.2 102.8 23.2 97.1 102.8
                CHI 95.1 102.1 22.3 95.4 102.1

                Comments: I mentioned Sacramento's very high offensive efficiency
                (110 a month ago) and San Antonio's excellent defensive efficiency
                (90 a month ago) as being unsustainable. Well, Sacramento's offense
                has fallen off by two points (and their sub-par defense improved by
                one), so I was right there. San Antonio's defense has yet to fall
                off significantly, though, and their offense continues to be among
                the NBA's least efficient. San Antonio also faced the weakest first
                half schedule of any Western team (Sacramento faced the second-
                weakest), so the true test will be the second half. These two teams
                have yet to play each other, so we have four games between the
                irresistable force and the immovable object to look forward too.

                Other strong offenses & defenses: Houston has improved its numbers
                by about two in either direction, much of that presumably
                attributable to Yao's continued development. Anyone else think this
                team could be very dangerous come playoff time? Their achilles heel
                is their low offensive floor% - when it comes to crunch time, can
                their offense come through with the needed buckets? Dallas is back
                on top of the NBA's offenses, though they're doing it differently
                this year. Their shooting is down (with Walker throwing up all
                those bricks, that's a given), but their offensive rebounding is way
                up, thanks to Jamison, Fortson, and Howard, primarily. That makes
                their offensive numbers much more sustainable, in my mind, than
                Sacramento's, which are based on continued amazing shooting from
                within and without the arc.

                Other notes: Orlando's defense is on pace to be one of the worst in
                NBA history. Seattle is taking 30% of their shots behind the arc,
                resulting in a floor rating of 100 and an offensive rating of 104.
              • igor eduardo küpfer
                ... From: ssims22000 To: Sent: Wednesday, January 28, 2004 5:08 PM Subject: [APBR_analysis] Re: Team
                Message 7 of 18 , Jan 28, 2004
                  ----- Original Message -----
                  From: "ssims22000" <ssims2@...>
                  To: <APBR_analysis@yahoogroups.com>
                  Sent: Wednesday, January 28, 2004 5:08 PM
                  Subject: [APBR_analysis] Re: Team Ratings (adjusted for schedule strength)


                  > The team ratings are updated through Jan. 27. I didn't have time
                  > to include a home/away modifier, so all ratings are calculated the
                  > same as before.
                  >

                  I may have missed this the first time around, but how are you adjusting for
                  opponent strength? Just this season's performance, or are you including
                  previous season(s)?

                  ed
                • Mike G
                  ... I m curious whether your ratings add anything beyond what Jeff Sagarin offers: http://www.usatoday.com/sports/sagarin/nba0304.htm He uses
                  Message 8 of 18 , Jan 29, 2004
                    --- In APBR_analysis@yahoogroups.com, "ssims22000" <ssims2@i...>
                    wrote:
                    > The team ratings are updated through Jan. 27. I didn't have time
                    > to include a home/away modifier, so all ratings are calculated the
                    > same as before.

                    I'm curious whether your ratings add anything beyond what Jeff
                    Sagarin offers:

                    http://www.usatoday.com/sports/sagarin/nba0304.htm

                    He uses point-differential, rather than off/def efficiencies. It
                    seems to me a team's scoring differential is going to be equivalent
                    to their efficiency differential. Whether they are better on
                    offense or on defense is another matter; but whether team A is
                    better than team B, does one need that distinction?

                    Sagarin does use home/away in his SOS deduction. He ranks the
                    Kings' SOS as #24 in the league (Spurs at #17).

                    In your eXpected Wins column, I guess you are assuming a balanced
                    schedule for everyone ?

                    >
                    >
                    >
                    > Team ORate DRate XWins OFlR DFlR
                    > SAN 97.3 90.7 59.6 98.9 91.8
                    > SAC 108.1 101.0 59.3 105.9 102.0
                    > MIN 103.6 98.0 56.1 105.3 97.7
                    > LAL 102.8 98.1 54.2 104.8 98.4
                    > HOU 98.1 93.5 54.2 96.2 93.0
                    > IND 99.3 94.7 54.1 98.8 95.8
                    > DAL 108.9 103.9 54.1 107.3 102.9
                    > DET 99.5 95.3 53.2 100.4 96.0
                    > MEM 102.4 99.6 48.8 102.3 100.0
                    > DEN 100.7 98.3 47.8 101.5 99.6
                    > MIL 102.2 100.7 45.0 102.2 100.9
                    > NJN 96.7 95.4 44.8 97.1 95.0
                    > NOR 99.5 99.1 42.2 98.1 98.8
                    > UTA 101.4 101.6 40.6 104.1 101.1
                    > BOS 100.1 100.4 40.2 97.9 99.1
                    > SEA 104.1 105.1 38.3 99.9 104.0
                    > GSW 100.3 101.7 37.0 100.3 101.1
                    > LAC 102.3 103.8 36.9 102.9 104.4
                    > NYK 98.2 99.8 36.3 96.7 99.9
                    > PHI 97.3 99.3 35.4 97.9 98.4
                    > PHO 98.3 101.0 33.5 98.5 100.4
                    > POR 102.4 105.8 31.6 103.7 105.6
                    > CLE 97.5 100.8 31.5 99.7 100.2
                    > MIA 97.0 100.8 30.3 96.5 100.6
                    > TOR 93.9 98.1 28.7 93.3 99.8
                    > ORL 101.8 108.0 24.8 101.2 107.7
                    > WAS 94.5 100.9 23.6 95.5 100.8
                    > ATL 96.2 102.8 23.2 97.1 102.8
                    > CHI 95.1 102.1 22.3 95.4 102.1
                    >
                  • ssims22000
                    ... time ... the ... equivalent ... The purpose of my ratings is a little different than Sagarin s. If you just want to look at which team is better, and that
                    Message 9 of 18 , Jan 29, 2004
                      --- In APBR_analysis@yahoogroups.com, "Mike G" <msg_53@h...> wrote:
                      > --- In APBR_analysis@yahoogroups.com, "ssims22000" <ssims2@i...>
                      > wrote:
                      > > The team ratings are updated through Jan. 27. I didn't have
                      time
                      > > to include a home/away modifier, so all ratings are calculated
                      the
                      > > same as before.
                      >
                      > I'm curious whether your ratings add anything beyond what Jeff
                      > Sagarin offers:
                      >
                      > http://www.usatoday.com/sports/sagarin/nba0304.htm
                      >
                      > He uses point-differential, rather than off/def efficiencies. It
                      > seems to me a team's scoring differential is going to be
                      equivalent
                      > to their efficiency differential. Whether they are better on
                      > offense or on defense is another matter; but whether team A is
                      > better than team B, does one need that distinction?
                      >
                      The purpose of my ratings is a little different than Sagarin's.
                      If you just want to look at which team is better, and that is all
                      you care about, use his ratings - his rating model is a lot more
                      sophisticated. After all, I am just using a clunky Pythagorean
                      approximation. A bell curve like Dean uses would be more accurate,
                      but it would require me to use a matrix of game scores, and that's a
                      bit too time-consuming for me right now. All I want out of my
                      overall team ratings is an approximation of how well each team is
                      doing. One small note - the results are a bit different because I
                      don't set a team's possessions equal to its opponents' possessions.
                      So a team which, for some reason, has 0.7 fewer possessions / game
                      than its opponents will rate better than it would if pure
                      differential were used. I do this because using pure possessions
                      like this gives more accurate offensive & defensive ratings, and
                      that's what I'm really after here.
                      Offensive and Defensive ratings, in my opinion, give more useful
                      information about a team than just a rating saying how "good" the
                      team is. These ratings start to answer the question of how a team
                      is good (or bad). For instance, someone just looking at the Sagarin
                      ratings for Orlando might be bewildered as to how a team that was in
                      the playoffs a year ago could be so bad. Look at their defensive
                      rating, though. Here we see some epic-level bad defense. OK, that
                      explains things. If you want to know why they are so bad
                      defensively, you'd have to go deeper than this. I have some other
                      quick stats that can help elucidate the factors that make an offense
                      or defense perform the way it does (I took most of these from Dean's
                      book, as well): true shooting percentage (we're all familiar with
                      this one, right?), free throw ratio (as Dean defines it, free throws
                      MADE / field goals attempted - you could combine these first two
                      into a scoring efficiency number, as well, though looking at them
                      separately tells you more about how they score), offensive
                      rebounding percentage & turnover percentage (turnovers /
                      possessions). These cover all of the factors going into an
                      offensive (or defensive) rating. The floor percentage (or floor
                      rating, as I have it here - a modification of Dean's formula) is an
                      alternate efficiency rating that measures how often a team scores.
                      Sometimes consistency counts more than pure efficiency (points per
                      possession).
                      I didn't include the extra indicators for space reasons, but here
                      are some for a few interesting offenses & defenses (league average
                      floor percentage (Flr%) is 48.2, true shooting percentage (TSP)
                      46.8, free throw ratio (FTR) 22.1, offensive rebound % (Off) 28.7 &
                      turnover percentage (TO%) 16.7):

                      Offense Rating Flr% TSP FTR Off TO%
                      Dallas 108.90 51.6 48.3 20.7 31.3 13.1
                      Sacramento 108.15 51.5 51.2 24.6 27.3 15.1
                      Seattle 104.08 48.0 49.8 19.9 26.7 16.0
                      Minnesota 103.62 50.9 49.1 19.5 26.2 14.1
                      AVERAGE 100.00 48.2 46.8 22.1 28.7 16.7
                      San Antonio 97.25 47.8 46.3 22.0 29.0 16.9
                      Toronto 93.85 45.2 45.3 20.3 24.2 16.7

                      Defense Rating Flr% TSP FTR Off TO%
                      San Antonio 90.70 44.2 42.3 21.0 25.7 17.0
                      Houston 93.51 44.9 42.5 22.7 25.9 15.2
                      Indiana 94.71 46.0 45.5 22.0 26.2 18.2
                      Detroit 95.25 46.0 44.6 18.8 28.0 17.1
                      AVERAGE 100.00 48.2 46.8 22.1 28.7 16.7
                      Dallas 103.88 49.8 49.3 19.8 29.1 15.7
                      Orlando 108.03 51.4 49.2 22.0 31.8 15.5

                      Note that these other indicators are not adjusted for schedule
                      strength.

                      > Sagarin does use home/away in his SOS deduction. He ranks the
                      > Kings' SOS as #24 in the league (Spurs at #17).
                      >
                      I don't use home & away for two reasons: 1) it would be too much
                      work and 2) I intend these rating primarily as whole-season analysis
                      tools, and over a whole season, each team plays a balanced or close
                      to balanced schedule with respect to home and away. The Spurs'
                      schedule rates worse in my system because they have played more road
                      games than home games against the better East teams (this will
                      eventually even out).

                      > In your eXpected Wins column, I guess you are assuming a balanced
                      > schedule for everyone ?
                      >
                      Yes. It's simply the projection based on offensive & defensive
                      ratings, everything else being equal.
                    • ssims22000
                      ... adjusting for ... including ... Just this season s.
                      Message 10 of 18 , Jan 29, 2004
                        --- In APBR_analysis@yahoogroups.com, igor eduardo küpfer
                        <igorkupfer@r...> wrote:
                        > I may have missed this the first time around, but how are you
                        adjusting for
                        > opponent strength? Just this season's performance, or are you
                        including
                        > previous season(s)?
                        >
                        Just this season's.

                        > ed
                      • Dean Oliver
                        ... time ... the ... Sagarin s stuff is a little bit of overkill for the NBA. Doing simple evaluation of schedule strength and home/road easily accounts for
                        Message 11 of 18 , Jan 31, 2004
                          --- In APBR_analysis@yahoogroups.com, "Mike G" <msg_53@h...> wrote:
                          > --- In APBR_analysis@yahoogroups.com, "ssims22000" <ssims2@i...>
                          > wrote:
                          > > The team ratings are updated through Jan. 27. I didn't have
                          time
                          > > to include a home/away modifier, so all ratings are calculated
                          the
                          > > same as before.
                          >
                          > I'm curious whether your ratings add anything beyond what Jeff
                          > Sagarin offers:
                          >
                          > http://www.usatoday.com/sports/sagarin/nba0304.htm
                          >
                          > He uses point-differential, rather than off/def efficiencies. It
                          > seems to me a team's scoring differential is going to be equivalent
                          > to their efficiency differential. Whether they are better on
                          > offense or on defense is another matter; but whether team A is
                          > better than team B, does one need that distinction?
                          >

                          Sagarin's stuff is a little bit of overkill for the NBA. Doing
                          simple evaluation of schedule strength and home/road easily accounts
                          for things well enough. Sagarin's evaluation goes above and beyond
                          and makes sense for college where varying schedules are huge.

                          So, yeah, Sagarin's overall evaluation should be roughly comparable.
                          It's just more interesting to look at the offensive and defensive
                          ratings separately. Tells a better story.

                          DeanO
                          www.basketballonpaper.com
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