- Jul 1, 2005Is there some prize that's really worth it? That's why we can't do

handicap competitions as an official event because there's no sure way

to ensure honesty. For non-official events, and all that other sort,

such as Sunday contests, or speedcubing.com averages, so far, we've

been relying on the honesty of the cubers, and it's been working in my

opinion. There really aren't that many doubtful records, and if

someone lies, I personally don't care, because your sub-14 average on

speedcubing.com means nothing to me if I beat you in a tournament.

If you end up posting a fake average, then you waste the rest of your

life trying to protect this lie, and trying to prevent people from

finding out the truth. You're reduced to nothing more than a person

who makes up excuses on why his times are so slow. It's just not worth

it :-P

Tyson Mao

MSC #631

California Institute of Technology

On Jul 1, 2005, at 9:17 AM, Dan wrote:

> Yeah but that's the problem with anything involving people.

>

> What's to stop me from posting an average of 15.00 on UWR list, even

> thought I've never been under 16? And it's not that unbelievable

> really. But it might be a bit odd, statistically, I might post a

> fake average where all the hundredths of a second were under .50 for

> example, which is statistically very unlikely. It's also unlikely,

> given enough cubes, that you would beat your long term average by

> more than 3 SD's.

>

> But yeah, I agree with you, but if people want to cheat, then

> they're only really cheating themselves.

>

> Dan :)

>

> --- In speedsolvingrubikscube@yahoogroups.com, Sachin Shirwalkar

> <sachin_civilian@y...> wrote:

>> No Dan but there is a way to beat this. If you are

>> considering only the best improvement done by a person

>> then I'll do my worst times in the first 30 solves and

>> then in the real solves i'll solve normally. So my

>> scores come out far better than the 30 previous ones.

>>

>> Though this looks like a good idea. Keep working on

>> this.

>>

>> Sachin

>>

>>

>> --- Dan <dan_j_harris@n...> wrote:

>>

>>

>> ---------------------------------

>> Hi Leyan, Tyson,

>>

>> The 30 - 40 solves would have to be fairly near the

>> time of the

>> competition, yes. As you say, if you were using an out

>> of date

>> statistic, it wouldn't work, because people's long

>> term averages

>> would slowly increase as they improved.

>>

>> This, in my opinion, is the main stumbling block of

>> this method, how

>> would you get all the competitors to bother to time 30

>> or 40 solves,

>> before the day of the tournament? Perhaps everyone

>> should time as

>> many cubes as they possibly can, in a practice session

>> before the

>> competition or so.

>>

>> Well, I guess we will just have to see what happens on

>> July 16th!

>>

>> Dan :)

>>

>> --- In speedsolvingrubikscube@yahoogroups.com, Leyan

>> Lo

>> <leyanlo@g...> wrote:

>>> Where would you get the 30 solves?

>>>

>>> If you're using solves that span a large time frame,

>> this is not a

>> good

>>> idea because most people get faster the more they

>> cube. It would

>>> probably be more fair to fit their solve times to an

>> exponential

>> decay

>>> curve up to a constant as a function of time, and

>> then calculate

>> their

>>> expected average and standard deviation for the day

>> of the

>> tournament

>>> from the fit.

>>>

>>> Leyan

>>>

>>> PS. From the statistics class I took, I remember

>> the number 40

>> (Law of

>>> large numbers).

>>>

>>>

>>> Dan wrote:

>>>> Hi Everyone,

>>>>

>>>> I would like some input on the following method

>> for judging a

>>>> handicap competition, especially whether it is

>> actually feasible

>> to

>>>> use in a competition!

>>>>

>>>> 1. From each competitor, have a long term Mean and

>> Standard

>>>> Deviation Statistic. From my Statistics course a

>> long tim ago,

>> the

>>>> number 30 seems to ring a bell in my head, ie you

>> have to make

>> 30+

>>>> solves before the statistics becomes valid.

>>>>

>>>> 2. After the competition, calculate each

>> competitors average.

>> Then

>>>> calculate a Normal Probability, with competition

>> average as

>> the "x"

>>>> statistic, and using the long term Mean and SD.

>> This will

>> calculate

>>>> the probability of the competitor achieving this

>> competition

>>>> average, if they were to make many thousands of

>> averages.

>>>>

>>>> 3. The competitor who has achieved the lowest

>> average

>> probability

>>>> would win, and competitors are ranked in order of

>> ascending

>>>> probabilities.

>>>>

>>>> So, all fine in theory?

>>>>

>>>> I have tried plugging some numbers into a

>> spreadsheet, and the

>>>> results are quite promising. But one observation I

>> have made, is

>>>> that in real life, results don't seem to "quite

>> fit" the normal

>>>> distribution. It is perfectly likely for someone

>> who is quite

>>>> consistent in practice, to have a wildly varying

>> average in

>>>> competition, and the probabilities end up being

>> almost 0, or

>> almost

>>>> 1. Is there someway of "stretching" the margins of

>> the normal

>>>> probability, so it can cover a wider range of

>> results? One way

>> would

>>>> be to multiply the competitors standard deviations

>> by a factor,

>> but

>>>> is this mathematically valid?

>>>>

>>>> Any help is greatly needed :)

>>>>

>>>> Dan Harris - www.cubestation.co.uk :)

>>>>

>>>> P.S. I hated Statistics in college ;)

>>>>

>>>>

>>>>

>>>>

>>>>

>>>> Yahoo! Groups Links

>>>>

>>>>

>>>>

>>>>

>>>>

>>>>

>>>>

>>

>>

>>

>>

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