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Re: streaks

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  • 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 1 of 6 , Aug 17 10:40 AM
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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 2 of 6 , Aug 17 11:58 AM
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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 3 of 6 , Aug 29 6:26 PM
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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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