Re: [APBR_analysis] Re: streaks
- 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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--- 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%)
> 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%)
> 11-21 finish (55%)
> 45-37 season
Nothing weird here either.
> San Diego 23-20 start
> 1-16 (1.3%)
> 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.)
Journal of Basketball Studies