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Re: [APBR_analysis] Re: streaks

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  • Charles Steinhardt
    I really need to dig up that paper... :)
    Message 1 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 2 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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