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Re: [APBR_analysis] Re: streaks

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  • John Grasso
    ... The 6-4 wasn t quite at the end of the season - after that hot streak they went 4-19 to finish the season - still they won 10 of their 15 victories in
    Message 1 of 6 , Aug 17, 2001
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      > > Cleveland - 0-15 start (4.8%)
      > > 1-0 (18.3%)
      > > 0-12 (8.9%)
      > > 1-0 (18.3%)
      > > 0-7 (24.3%)
      > > 1-0 (18.3%)
      > > 0-3 (54.6%)
      > > 2-0 (3.4%)
      > > 0-7 (24.3%)
      > > 6-4 (0.4%)
      > > 4-19
      > > 15-67 season
      >
      > Only the 6-4 finish is that surprising. My sense, too, is that this
      > kind of streak can definitely happen at the end of a bad season when
      > no one cares about you.

      The 6-4 wasn't quite at the end of the season - after that hot streak they
      went 4-19 to finish the season - still they won 10 of their 15 victories in
      their last 33 games. After the first 40 games they had only won 3 games and
      those were against the other two expansion teams. Their first win against an
      established team was over Philadelphia around Christmas.
    • Dean Oliver
      ... Something I realized about this analysis is that there are a lot of _possible_ streaks in a season. Though the 7-0 streak at the end had a 0.7% chance of
      Message 2 of 6 , Aug 17, 2001
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        --- In APBR_analysis@y..., "John Grasso" <johng@s...> wrote:
        > I've recently being doing some research on the 1970-71 NBA season
        >
        > San Diego 23-20 start
        > 1-16
        > 8-2
        > 1-4
        > 7-0 finish (all home games)
        > 40-42 season

        Something I realized about this analysis is that there are a lot of
        _possible_ streaks in a season. Though the 7-0 streak at the end had
        a 0.7% chance of happening, there were 75 possible sequences of 7
        games for this to happen in the season. Hence, the odds of this kind
        of team having 1+ series of 7 consecutive wins in a season are 39%.
        No big deal.

        On the other hand, the 1-16 streak was pretty strong. A 40-42 team
        has a 0.02% chance of going 1-16 in 17 games. There are about 55
        possible 17 game streaks in an 82 game season. The odds of any 40-42
        team having this kind of streak in an 82 game season are 1.1%. That
        is pretty impressive.

        Back to the Sting. They have a shorter season, only 32 games. The
        odds of having 1+ streak of 1-10 is 3.5% -- pretty unusual. The odds
        of having a 17-4 streak or better is 17%, not a big deal. Multiplying
        again (gulp), this makes for a 0.60% chance of such a season.

        Dean Oliver
        Journal of Basketball Studies
      • Charles Steinhardt
        I really need to dig up that paper... :)
        Message 3 of 6 , Aug 17, 2001
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          I really need to dig up that paper... :)

          On Fri, 17 Aug 2001, Dean Oliver wrote:

          > --- In APBR_analysis@y..., "John Grasso" <johng@s...> wrote:
          > > I've recently being doing some research on the 1970-71 NBA season
          > >
          > > San Diego 23-20 start
          > > 1-16
          > > 8-2
          > > 1-4
          > > 7-0 finish (all home games)
          > > 40-42 season
          >
          > Something I realized about this analysis is that there are a lot of
          > _possible_ streaks in a season. Though the 7-0 streak at the end had
          > a 0.7% chance of happening, there were 75 possible sequences of 7
          > games for this to happen in the season. Hence, the odds of this kind
          > of team having 1+ series of 7 consecutive wins in a season are 39%.
          > No big deal.
          >
          > On the other hand, the 1-16 streak was pretty strong. A 40-42 team
          > has a 0.02% chance of going 1-16 in 17 games. There are about 55
          > possible 17 game streaks in an 82 game season. The odds of any 40-42
          > team having this kind of streak in an 82 game season are 1.1%. That
          > is pretty impressive.
          >
          > Back to the Sting. They have a shorter season, only 32 games. The
          > odds of having 1+ streak of 1-10 is 3.5% -- pretty unusual. The odds
          > of having a 17-4 streak or better is 17%, not a big deal. Multiplying
          > again (gulp), this makes for a 0.60% chance of such a season.
          >
          > Dean Oliver
          > Journal of Basketball Studies
          >
          >
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        • Dean Oliver
          ... Given the extra work I did to evaluate the odds of a x% team having a streak of a certain type, I figured I d go back to this post and post the actual odds
          Message 4 of 6 , Aug 29, 2001
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            --- In APBR_analysis@y..., "John Grasso" <johng@s...> wrote:

            Given the extra work I did to evaluate the odds of a x% team having a
            streak of a certain type, I figured I'd go back to this post and post
            the actual odds of such a streak occurring. Low values, less than 5%,
            are considered pretty unusual.

            >
            > Cleveland - 15-67 for the season
            > 0-15 start (96.6%)
            > 1-0 (100%)
            > 0-12 (99.9%)
            > 1-0
            > 0-7
            > 1-0
            > 0-3
            > 2-0
            > 0-7
            > 6-4 (25%)
            > 4-19 finish
            >

            Nothing statistically unusual here. Even the 6-4 streak isn't that
            unusual for such a team.

            >
            > Detroit 12-1 start (29%)
            > 0-6 (48%)
            > 11-7
            > 11-2
            > 11-21 finish (55%)
            > 45-37 season
            >

            Nothing weird here either.

            > San Diego 23-20 start
            > 1-16 (1.3%)
            > 8-2
            > 1-4
            > 7-0 finish (all home games) (39%)
            > 40-42 season
            >

            The 1-16 run was weird. Everything else is normal.

            > Portland finished season
            > 5-0 (35%)
            > 2-14 (94%)
            > 5-0 (35%)
            > 29-53 season

            The odds of having 2 5-0 streaks is only 7%, so that may be a little
            weird. Otherwise, nothing statistically unusual.

            This really points out the old Tversky research that the mind
            perceives streaks a lot faster than stats would suggest they are
            really happening. Basically, if your mediocre team wins 5 or 7 in a
            row, it may not mean anything. It happens a lot to mediocre teams, as
            John pointed out here.

            I even ran the numbers on the 69-13 Lakers that won 33 straight. The
            likelihood of a random 69-13 team winning 33 straight is 15%, not that
            unusual for such a good team. It was more unusual to have a team that
            good throughout the season. This basically proves that the
            Lakers didn't win 69 by fluke. A 60-22 team wins 33 straight only
            0.17% of the time. A 65-17 teams wins 33 straight only in 2.3% of
            their seasons. What was the Bulls longest streak in their 72 win
            season? (Interestingly, I calculate that they had about a 50% chance
            of having a run of 33-0 in that season.)

            Dean Oliver
            Journal of Basketball Studies
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