The Efficiency of the Bookies Market

[La Mer]

With the discussion going on in some other themes about longshots, ratings etc, when considering what could be termed 'market efficiency' it has been a long-held belief by many that the bookmakers market is the best guide, but not necessarily always correct, for the real chances of each individual horse in any given race.

This is certainly true in a broad sense at the very least.

Over the last few years however with weak on-track markets that efficiency has come under strain, particularly with the bookies opening markets, albeit that by race-start time a degree of efficiency has been reached, more so in Sydney than in any other, often with over-rounds of under 110% with an average of around 115%.

While not attempting how to tell others to suck eggs, for those that might not know what an over-round is: well it is the total percentages of all the runners/participants/outcomes in any given event, e.g. in the current 2nd test match between Australia & South Africa at the close-of-play on day 3 the respective odds of the three possible outcomes are:

TAbcorp Sportsbet:
Australia: $1.55 (64.5%)
South Africa: $9.00 (11.1%)
Draw: $2.80 (35.7%)
Total Percentage/Over-round = 111.3%
(Brackets indicate odds converted to percentages)

Many would argue (including me) that in a three outcome event an over-round of 111.3% is not that efficient, and it ain't when considered to the odds offered by Betfair (a short while ago):

Betfair:
Australia: $1.63 (61.3%)
South Africa: $12.00 (8.3%)
Draw: $3.25 (30.7%)
Total Percentage/Over-round = 100.3%
(Brackets indicate odds converted to percentages)

Overall an 11% advantage to those wagering on Betfair, on which at this stage there has been just under AUD$11 million matched.

Which brings me to the main point, the one at the start of this message, which is that the long-held belief the bookmaker's markets are the most efficient. Well, if the bookmaker’s markets are substituted with Betfair's they are.

Betfair in the UK recently published the following:

"Betfair prices are actually extraordinarily accurate reflections of a horse's chance of winning a race.

And it's worth remembering that this is historical data and not a predictor of future events. It also looks at average weighted prices – which isn’t something you can know until after the event. And there's commission to take into account. The value of investments can go down as well as up and all that.

The full results are below. We’ve grouped all the horses into price ranges – averaging the expected win rate and the actual win rate:

Price Banding / Average EXPECTED win rate / Average ACTUAL win rate / Difference

1.01-2............64.38%..........4.84%.........0.46%
2.01-4............36.61%.........36.88%.........0.27%
4.01-6............20.27%.........20.66%.........0.39%
6.01-10..........12.77%..........12.60%........-0.17%
10.01-20..........6.93%............7.18%........0.25%
20.01-100.........2.64%............2.56%.......-0.08%
100.01-1000......0.30%............0.26%.......-0.04%

How did we work this out?

We grouped all the horses at various prices. As an example, if a horse was 1.5, then we said that the market was theoretically saying that it had a 66.6% chance of winning the race (100 divided by the price). This gave us the “Expected win rate”.

We then checked how often they actually did win – the “Actual win rate”.

In this example, if 1.5 shots won more than 66.6% of the time, then the “Difference” would be positive – meaning that you’d have made a profit backing all of them.

We looked at all the Win markets from UK racing, jumps and flat, from 1st January 2004. We excluded any race that hadn’t a traded volume of more than £50,000.

We took the weighted average price that each horse traded prior to the off (so not including in-play) – over 157,000 horses in total. These were then grouped into the bands you see above and averages taken."

So what this table clearly indicates is the actual win outcomes are very much in accordance with the expected win outcomes.

The favourite/longshot bias that may exist in other markets certainly do not exist in the Betfair markets.

[KennyVictor]

Those figures are remarkably close. Thanks for that very interesting post.

KV

[jacfin]

La Mer
Interesting figures indeed.
It has always astounded me that the public can get it so right over so many races.
I have seen several studies where the SP market is shown to be far more accurate than even the best ratings over a large sample. The trick for ratings people,of course, is to find the race where the public have it wrong.

[KennyVictor]

I suppose an interesting question might be that although the public may be getting it right over time as proved by those averages how right do they get it race by race? If odds on offer varied a lot race by race from the actual chances of winning we could still expect to turn a nice profit by betting on the right horses in the right races.


KV

[punter57]

Yes, Kenny that is the question,indeed. However, "statistically" seen the result is "right" every time for Betfair, as stats ONLY work in the long run (they are viewed AFTER THE EVENT, aren't they?) ie toss a coin; 50/50 chance but STILL a 100% chance of one result being correct and the other one NOT. After the 2nd toss (if it comes down on the other side) we say "see 50/50" and so on. Even if it ends up 505 heads to 495 tails it's "close enough" There is no "stat" however, which tells you the outcome of the NEXT event. They are ALWAYS simultaneously 50/50 BUT 100% certain of not being 50% right.
While there seems no way to "predict" each occurence ONE AT A TIME with coins (ie all things REALLY are equal), it is not like this with horses (or sports). Apply the coins/roulette/dice idea to horses and what you actually need is an "error" in the "apparatus" to get an edge (with coins; if you picked up that the face was significantly heavier than the taill, for example). This means, (for the races),finding an underrated (undervalued, underestimated) horse that ON THE DAY was/is, in reality (as with stats,we look AFTER the event) 100% certain or close to it. Like the coin analogy we are looking for something "wrong" (right!!!).. Once again, we then need to discover ON THE DAY what will allow this horse to over-run the others. What "advantage" has it got?
What we want therefore is access to "total knowledge" or, failing that, every trainer's words and THOUGHTS. We want the trainer to tell us the unvarnished truth about their horse.. They should let us know that the tracktimes are "suspect" (ie slower or faster) because the jockey was taking it easy or really pushing it. Or that the favoured horse seemed "grumpy" this morning, or that D. Beadman is under instructions to do......whatever, or that the real target is next week's race; or that the trainer has put the horse over 2000 m as a "practice" etc etc. But they don't. We have to deduce it!!
Well, how do we deduce what other people (our partners, mates,business associates) are REALLY thinking?? Well??? How do we know when the "boss" is annoyed Or happy,WITHOUT THEM TELLING US? . You already know!! Cheers.

[Dale]

La Mer

I have seen several studies where the SP market is shown to be far more accurate than even the best ratings over a large sample. The trick for ratings people,of course, is to find the race where the public have it wrong.

Its not just ratings people that try to find the races where the public have it wrong.

Most ratings people work through race by race waiting for a discrepency,others like myself try to locate those descrepecies before the start of the day.

It's true that odds like those above are a very acurate representation of the actual chance of horses in certain price ranges BUT what isnt so obvious is that many of the horses in say the 10 to $20 price range have a far greater chance than their odds suggest,likewise many have a far worse chance.

The winning % to odds comparison provided by La Mer is just an average taken from thousands of races,individualy the horses odds mean nothing and if you pick and choose your horses its not too hard to find descrepencies.

I'm of the opinion that these descrepencies are easier to find with longer priced horses.

[Bhagwan]

A Bookies open price rankings e.g. IAS opening price ,of the top 4 rankings has a slightly greater SR than say the TAB top 4 price rankings or Pre-post market top 4 rankings.



What one can do with this is ,only bet if ones selection is also in the Bookies top 4 price rankings.
The Bookies ranking is around the 75-80% mark for their top 4 getting up.

[jfc]

A cute relevant UK insanity according to this Bolshy rag:

http://sport.guardian.co.uk/horseracing/comment/0,10148,1676770,00.html

Apparently Betfair puts so much pressure on on-course prices that the official SP is now inching higher.

So relevant dinosaurs now want to introduce an alternate "industry friendly" SP!

The current local SP may often be a farce for the obvious reason that often there aren't that many relevant bookmakers about to produce a true market figure.

An alternative official SP based on something like the weighted average of TABs, Betfair and any other licensed outfit prepared to disclose turnover statistics within 30 seconds after race jump, would make considerably more sense.

But I won't be holding my breath for such market glasnost.

[woof43]

Yes, Kenny that is the question,indeed. However, "statistically" seen the result is "right" every time for Betfair, as stats ONLY work in the long run (they are viewed AFTER THE EVENT, aren't they?) ie toss a coin; 50/50 chance but STILL a 100% chance of one result being correct and the other one NOT. After the 2nd toss (if it comes down on the other side) we say "see 50/50" and so on. Even if it ends up 505 heads to 495 tails it's "close enough" There is no "stat" however, which tells you the outcome of the NEXT event. They are ALWAYS simultaneously 50/50 BUT 100% certain of not being 50% right.
.
Punter 57 The two-factor probability brings up an interesting category of study... understanding probabilities that aren't exactly straight-forward, or are counter-intuitive. For a person wagering cash money on races, having a firm foundation in probability is a must. Yet all too many people don't! (So much the better for those that DO!
So here's a simple little probability problem to get started. (I'll post the answer later, if need be)
You are told that a family has two children. You are also told that one of those two children is a girl. Assuming that the biological probability of having either a boy or a girl baby is equal (50-50) then what is the probability that the family ALSO has a boy?

Enjoy

[La Mer]

You are told that a family has two children. You are also told that one of those two children is a girl. Assuming that the biological probability of having either a boy or a girl baby is equal (50-50) then what is the probability that the family ALSO has a boy? Enjoy

25%.

[Sahasastar]

50%

[kenchar]

100%

[slowman]

50%

[DR RON]

50 % What do we win for the right answer?

[slowman]

a date but it depends what side of the fence your on

[jfc]

I figure the probability of the other child being a boy is 2/3. But then I'm not a consensus creature.

Woof, in the highly unlikely event that your admirable educational initiative takes off, maybe you can then start a dedicated thread.

[NANOOK]

12.5%

[TWOBETS]

What a great teaser. To me this is horse racing all over, as we think we are told the relevant facts but in fact we know diddly squat.

How many children does the family have? We might think that it's two but you might be wrong. Even though they have eighteen kids it is still correct to say that they have two kids . Even though they have twelve girls and six boys it is still correct to say they have one girl.

Is it any wonder I bet on favourites for the place?

[KennyVictor]

If the family has two kids and one of them is a girl the other must be a boy - right Kenchar?.


KV

[slowman]

you can have ten kids all the same sex if we are talking about the same odds as a coin being tossed,each shot is 50,50 and independent of the other..

.................cheers......slowman...........

[kenchar]

KV,
Might be a monkey too ( just joking ).
The way I look at it Woof has just used the family as an example.
The real question is you have a 50/50 scenario and one half of the 50 has gone so we should be left with the other 50 being 100%, but I could be wrong.
Woof could you PLEASE give us the answer, I can't eat or sleep and I am having nightmares ( they are the ones that race at Mooney Valley at night ) about this.

[Chrome Prince]

50% chance.

Chance has no memory.

So what's the chance that the family has two girls, and what's the chance it has two boys???

:D

[beton]

Each time at the well produces a 50/50 chance. one sperm in a billion getting through. However if the sire has allready produced one girl the likelihood of a repeat is higher than that of producing a boy. Atheletic types have a higher temperature and predominantly produce girls. There is all sorts of other criteria which may slightly change the odds.

A bit like horse racing.

Besides that I hope everybody had a good Christmas and has a prosperous New Year

[BJ]

Punter 57 The two-factor probability brings up an interesting category of study... understanding probabilities that aren't exactly straight-forward, or are counter-intuitive. For a person wagering cash money on races, having a firm foundation in probability is a must. Yet all too many people don't! (So much the better for those that DO!
So here's a simple little probability problem to get started. (I'll post the answer later, if need be)
You are told that a family has two children. You are also told that one of those two children is a girl. Assuming that the biological probability of having either a boy or a girl baby is equal (50-50) then what is the probability that the family ALSO has a boy?

Enjoy

Clearly 50%. The fact that there is a girl is just there to throw people off. It is irrelevant.

Assuming that the biological probability of having either a boy or a girl baby is equal (50-50)

Here is the answer.

[woof43]

Well, an interesting set of answers.
Here is the correct one:
2/3 or .667 -- the probability that the family also has a boy is 2/3. (cheers jfc)
And here's the logic:
You were told a family has two children. There are four possible ways in which a family can have two children:
#1 Girl-Girl (probability = .25)
#2 Girl-Boy (prob = .25)
#3 Boy-Girl (prob = .25)
#4 Boy-Boy (prob = .25)
Each of those four ways of having two children has an equal probability of happening, and those probabilities, of course, add up to 1.000. (as specified in the question: Assuming that the biological probability of having either a boy or a girl baby is equal 50-50).
You were told that one of the children was a girl. That only eliminates one possibility out of the four: Boy-Boy, leaving three other possibilities, (GG, GB, BG) all of equal probability. Of those three, two include a boy. Thus the probability that the family ALSO has a boy is 2/3 or .667.
The most common mistake that people make when confronted with this problem is that they try to reduce it to a simpler problem. The mistake is in thinking that the FIRST child was a girl, so what is the probability that the SECOND child is a boy. In that improperly simplified problem, you have eliminated TWO out of the four possible ways of having two children (Boy-Girl and Boy-Boy) leaving only two possibiliities, only one of which has a boy in it. And thus the mistaken 50% answer. The mistake was in eliminating Boy-Girl from the set of possible situations during the simplification.

thank you

[BJ]

Well, an interesting set of answers.
Here is the correct one:
2/3 or .667 -- the probability that the family also has a boy is 2/3. (cheers jfc)
And here's the logic:
You were told a family has two children. There are four possible ways in which a family can have two children:
#1 Girl-Girl (probability = .25)
#2 Girl-Boy (prob = .25)
#3 Boy-Girl (prob = .25)
#4 Boy-Boy (prob = .25)
Each of those four ways of having two children has an equal probability of happening, and those probabilities, of course, add up to 1.000. (as specified in the question: Assuming that the biological probability of having either a boy or a girl baby is equal 50-50).
You were told that one of the children was a girl. That only eliminates one possibility out of the four: Boy-Boy, leaving three other possibilities, (GG, GB, BG) all of equal probability. Of those three, two include a boy. Thus the probability that the family ALSO has a boy is 2/3 or .667.
The most common mistake that people make when confronted with this problem is that they try to reduce it to a simpler problem. The mistake is in thinking that the FIRST child was a girl, so what is the probability that the SECOND child is a boy. In that improperly simplified problem, you have eliminated TWO out of the four possible ways of having two children (Boy-Girl and Boy-Boy) leaving only two possibiliities, only one of which has a boy in it. And thus the mistaken 50% answer. The mistake was in eliminating Boy-Girl from the set of possible situations during the simplification.

thank you


OK. I think I misread the question. My thinking was that they were expecting another, what were the chances. I think that I missed the obvious wording of the question implying that the child was already born.
All makes sense now.

I presume that those of us that said 50% would be right provided that we were guessing the sex of the second unborn child?

[DR RON]

I'm with you on that BJ, I must of read the question the same way you did, basing my answer on the thinking the second child was yet to be born, but I should have given it a bit more thought. I always seem to rush in without thinking things through clearly.

Beton, My offspring in order are Boy Girl Boy. If I was at my athletic peak when producing the girl then I must have been in pretty bad shape when producing the Boys. :)

[KennyVictor]

You are told that a family has two children. You are also told that one of those two children is a girl.
At the risk of being seen as a bad loser (or looser in some circles) I consider this a badly worded question. Just the sort of question a study of statistics is likely to engender as we all know statisticians like their figures to mean what the statistician wants them to mean.

Scenario 1. A family has two children and one of them is a girl therefore it is logical to assume one of them isn't. I mean how many non statisticians would say "I have two children, one is a girl and the other is a girl."
So: Answer to the original question 100%

Scenario 2. We see a picture of the unfortunate statisticians children, they aren't attractive, in fact you can't tell what sex they are with their clothes on. The statistician points to one and says 'She is a girl'. What's the other one then we wonder and of course the answer is 50/50 it's a boy since it's a even chance either way.
So: Answer to the original question 50%

The 66% scenario is more of a play on words than a sensible question.

Well, someones gotta be controversial. Crash has dissappeared and P57 has a fortnight in the sin bin.

KV

[DR RON]

and P57 has a fortnight in the sin bin.

KV[/QUOTE]
No wonder the longshot thread is slipping down the pecking order!!

p.s could someone please tell me how to quote only part of a post? I highlighted part of the quote but the whole thing appeared on my reply anyway.

[woof43]

KV
The whole point about playing our handicapping game (and a lot of the "game of life") is being forced to make decisions even when faced with incomplete or conflicting information. And a person that is better at determining those probabilities and expectations in the handicapping domain, especially with uncertain information, gets paid more money in the long haul.

Thus a person that wants to progress in the game of handicapping has to first become reasonably proficient in probability and statistics, and then move on to heuristics and biases and the study of a couple or three aspects of psychology. We're all peeling the handicapping onion so to speak!

[lomaca]

p.s could someone please tell me how to quote only part of a post? I highlighted part of the quote but the whole thing appeared on my reply anyway.
Hi! You mean like this?
p.s could someone please
Just delete the part you don't want, or put what you want between "[QUOTE] and [QUOTE]"
As to the two children question, forget it!
He answered the wrong question.
The way it was asked there is only one answer to it, and KV got it right.

Cheers.

[DR RON]

Hi! You mean like this?

J


Yes . Thanks lomaca

[Chrome Prince]

The fact of what they have or don't already have, is irrelevant to the answer.

If I flip a coin and I already have one heads, I still have a 50% chance of tails next spin.

[Chrome Prince]

You are also told that one of those two children is a girl

There are four possible ways in which a family can have two children:
#1 Girl-Girl (probability = .25)
#2 Girl-Boy (prob = .25)
#3 Boy-Girl (prob = .25)
#4 Boy-Boy (prob = .25)


What is the difference between Girl-boy and Boy-Girl, they are the same thing.

Boy-boy is an invalid combination given the question.

There are two possible combinations

Girl Girl

Girl Boy

That's it.

[KennyVictor]

Of course a mathmatician, because he wouldn't want to create confusion, would ask the question thusly: "If at least one of the children is a girl" and then might get an answer other than 100% or 50%. But Woof's point is valid in that we have to get used to using half ar sed information if we want to win at handicapping (my phrasing not his).

KV

[AssumeTheCrown]

This problem is a classic case of conditional probability. The average person has trouble understanding it. The boy/girl problem can be tested by repeatedly tossing 2 coins and recording the results(say 20 times). There are 3 possible outcomes ( 4 really) - HH,HT,TT.
Now we ask what is the probability of the other coin being a TAIL given that one of them is a HEAD? Straight away we can ignore all the TT's from our sample (cross them off the list) because the question asks "given that one of them is a head". That will leave only HH's and HT's in the list. Now put a circle around any T in the list. You should find about a 2:1 ratio or a 2/3 to 1/3 Tails to Heads.

This better illustrates conditional probability. With the coin or the boy/girl examples there are 4 possible outcomes - HH, HT, TH, TT each with a 25% chance of occuring. When we ask the question "given that one of them is a ..." we are effictively saying that one of these situations did not happen. In the above example we eliminated TT leaving HT, TH, HH. Now we are left with 2 T's and 1 H with the corresponding H which we were told existed. So the probability of the other coin being a T is 2/3 and an H is 1/3.

[KennyVictor]

Well we have convincing arguments supporting 50%, 66% and 100% depending on how you read the question, what I would be interested to see now is the rationalle behind the other options offered. Nanook? La Mer? I particularly liked Kenchar's explanation. It surprised me at first but then made me realise that a standard view of statistics is absolutely not essential to being a successful punter.

KV

[La Mer]

Well we have convincing arguments supporting 50%, 66% and 100% depending on how you read the question, what I would be interested to see now is the rationalle behind the other options offered. Nanook? La Mer? I particularly liked Kenchar's explanation. It surprised me at first but then made me realise that a standard view of statistics is absolutely not essential to being a successful punter. KV

In my case it was by multiplying 0.5 by 0.5 which gives a result of 0.25, which would be correct other than for the issue of the prior knowledge of knowing that one of the children has already been identified as a girl.

[slowman]

i would like to hear jfc's thoughts on this becouse as it stands i'm wity cp...
...................cheers....slowman..................

[NANOOK]

I didn't really read the question and multiplyed 0.5x0.5x0.5.......don't really know why.......don't really care, but one thing I do know is that 98% of the population who suffer from heart disease own a colour television?

nanook

[Chrome Prince]

This problem is a classic case of conditional probability. The average person has trouble understanding it. The boy/girl problem can be tested by repeatedly tossing 2 coins and recording the results(say 20 times). There are 3 possible outcomes ( 4 really) - HH,HT,TT.
Now we ask what is the probability of the other coin being a TAIL given that one of them is a HEAD? Straight away we can ignore all the TT's from our sample (cross them off the list) because the question asks "given that one of them is a head". That will leave only HH's and HT's in the list. Now put a circle around any T in the list. You should find about a 2:1 ratio or a 2/3 to 1/3 Tails to Heads.

This better illustrates conditional probability. With the coin or the boy/girl examples there are 4 possible outcomes - HH, HT, TH, TT each with a 25% chance of occuring. When we ask the question "given that one of them is a ..." we are effictively saying that one of these situations did not happen. In the above example we eliminated TT leaving HT, TH, HH. Now we are left with 2 T's and 1 H with the corresponding H which we were told existed. So the probability of the other coin being a T is 2/3 and an H is 1/3.

I don't believe that two coins has any bearing on this situation.

We were told there was a 50% chance of something happening, we were told that one scenario had already happened. - a girl.

That still leaves a 50% chance.

Where did this extra coin come from?

Unless you count twins as one child :D

The available combinations given that one child is a girl is Girl-Boy, Girl-Girl, there is no way they can have boy-boy.

Boy-Girl is the same as Girl-Boy as they already have a girl.

[lomaca]

I don't believe that two coins has any bearing on this situation.

Hi CP!
That's why I told Dr Ron, that Woof had the right answer to the wrong question.

Statistics is a wonderful and indispensable tool in making sense of info, provided it is used the way it was meant to be used.
It has aquired a smelly and dubious reputation only because it is has been, and dare I say will be used in the future to prove things to be either true or false, when logic tells you otherwise.
Still let them prove what they want, as long WE use stats the right way!
Cheers

[AssumeTheCrown]

The coins example is no different to the boy/girl problem.
Where you are confused Chrome Prince is that the order IS important.
The sample space is in fact -

Boy/Boy
Boy/Girl
Girl/Boy
Girl/Girl

Where each outcome is a 1/4 or 25% chance of occuring.

So if the order is not spectific there is a 1/4(25%) chance of having 2 Boys, a 1/4(25%) chance of having 2 Girls and a 2/4(50%) chance of having a Boy/Girl (any order).


Now the problem is conditioned on the fact that there is "at least one girl" so the Boy/Boy scenario can be eliminated fom the sample space leaving -

Boy/Girl
Girl/Boy
Girl/Girl

Where each outcome is a 1/3 or 33% chance of occuring. Given that we have already singles out a Girl, we are left with a Boy in 2 out if the 3 possibilities. This leads to the 2/3 Boy and 1/3 Girl which happens to be the correct answer.

The hard part to comprehend is the wording of the question.

[jfc]

The fact of what they have or don't already have, is irrelevant to the answer.

If I flip a coin and I already have one heads, I still have a 50% chance of tails next spin.

CP,

Get your facts right.

Your coin metaphor is wrong.

Woof clearly stated that both of the 2 children were already begat.

You are wrongly suggesting otherwise when you talk about the 2nd flip of a coin.

The next part of the stated problem, involved X - an information provider (not necessarily a parent KV!) who secretly ascertained the gender of one child. Then if that child was not a girl X then checked the gender of the other to see if that one was a girl.

All that X disclosed was that one of those 2 children was a girl.

You don't know how many childrens' relevant details X examined.

X didn't say that the younger was a girl. Nor that the older was a girl.

KV has wrongly assumed that the parents are informing you that one of the children is a girl.

But you are not making assumptions. Instead you have invented a contradictory scenario.

There is no flipping of a 2nd coin. Both coins have already been flipped.

Enough coins have been examined to truthfully disclose whether a head has occurred.

After I figured the problem through I then googled to see whether this was a classic problem.

Got it in one.

http://mathforum.org/dr.math/faq/faq.boy.girl.html

Meanwhile some of you couldn't even do the right thing and check whether you had read the problem correctly in the first place.

Imagine the response you can expect next time you ask a stats related question.

[beton]

I tried hard to stay away from this. One billion sperm racing down the chute and the leader pulls up and lets the potential boy thru while saying "we have already been to the trough" Hard and fast the sperm has no prior memory etc This is a straight out 50/50 possible outcome.

At this point other factors arise. Most of these are statitical analysis of past results which have no direct bearing on this event. However people read their own interpretations from these results. The ratio of boys to girls is 50/50 and there is one girl already hence there is a 100% chance that this is a boy. Boy/girl and Girl/Girl is still only 50/50 because we are only dealing with the possible outcome so the factual portion (we already have a girl) is deleted leaving whether this one will be a boy or girl. Other factors may sutblely alter the odds ie a history of girls on both sides of the family,This area produces on average 75% girls or this is Amazonia and boys do not survive birth.
The only way to change it from 50/50 is to show that there is a greater proportion of one sex in the sperm count because nobody is going to say thatone sex swims faster than the other.

this is my only comment as i refuse to allow the quality of the forum to deteriorate.

Besides that I wish all a good day

[slowman]

jfc,i was just wondering if you get sea views from the mountain you live on.....

...........cheers....slowman...............

[KennyVictor]

The hard part to comprehend is the wording of the question.This is indeed the only correct answer. All other answers depend on the answer to this question.

KV

[DR RON]

Assuming that the biological probability of having either a boy or a girl baby is equal (50-50)



As far as I am concerned the above quote says it all. If there is a 50/50 chance of an event happening then what has happened before hand is irrelevent. JUst because the ratio of boys to girls born is 50/50 dosent mean to say a family cant have 2 girls and another family have 2boys. The ratio still stays the same.

can't wait for the follow up question woof. :)

[Chrome Prince]

Spot on DrRon,

I'm not wrong, and I don't understand if we've been told one is a girl already, why others cannot comprehend that Boy-Boy is an invalid combination.

Amazing.

[moeee]

jfc,i was just wondering if you get sea views from the mountain you live on.....

...........cheers....slowman...............

SLOWMAN

Did you know there are forums on the internet that are not gambling related?
Perhaps you could try a Google search using keywords like,
Forum,"bagging people","Low I.Q."

JFC is in fact one of my favourite contributors.
I don't quite understand his mathematics,but it sure sounds impressive.

[slowman]

you have had three weeks to work that joke out moeee and you still dont get???

[moeee]

3 WEEKS?
Have I?
Oh my GOD!

I must change my user name to SLOWMO!
Maybe I don't got a sense of humour like yours.
Maybe it would work better if you were wearing a clown suit or a big red nose,like the DRUNKARDS have?

[crash]

SLOWMAN

Did you know there are forums on the internet that are not gambling related?
Perhaps you could try a Google search using keywords like,
Forum,"bagging people","Low I.Q."

JFC is in fact one of my favorite contributors.
I don't quite understand his mathematics,but it sure sounds impressive.

JFC is a class act, Probably bipolar [I'm an espie: Aspergous syndrome, a mild version of autism] just like the handbrake is [bipolar] but we get on and understand each other. Check out 'wrong planet.com' to understand JFC and yours truly. I'm a long term member !!! :-) We are easily misunderstood. Imagine a zebra in a paddock of horses. Looks like a horse, eats like a horse but there is somthing not quite right..... Get the picture? Of course the zebra is a nice bloke but unsettles the horses no end. He can't help it, it's who he is :-)

[davez]

only one thing crash, your average tab/racetrack is full of zebras with a couple horses wandering around wondering what the **** is going on

[crash]

only one thing crash, your average tab/racetrack is full of zebras with a couple horses wandering around wondering what the **** is going on

I new it. I am normal after all [stupid child psychologists]. I feel totally comfortable at a race track. It's everyone else outside of the track that is a fruit-loop !!!

[davez]

It's everyone else outside of the track that is a fruit-loop !!!


amen to that!

[xptdriver]

JFC is a class act, Probably bipolar [I'm an espie: Aspergous syndrome, a mild version of autism] just like the handbrake is [bipolar] but we get on and understand each other. Check out 'wrong planet.com' to understand JFC and yours truly. I'm a long term member !!! :-) We are easily misunderstood. Imagine a zebra in a paddock of horses. Looks like a horse, eats like a horse but there is somthing not quite right..... Get the picture? Of course the zebra is a nice bloke but unsettles the horses no end. He can't help it, it's who he is :-)

Gday Crash

I know exactly where you are coming from... My partner has a 4 yo boy... He is autistic... can hardly put 2 words together without gibbering... But they (the so called experts) tell us he will learn to hide is autism as he gets older..
I feel that is unfair.. imagine having to hide who you really are just to be socially acceptable...

I have done a lot of reading on the subject and I obviously am no expert, but I am beginning to get an understanding of how autistic people operate. I have read many articles written by people who are autistic, and sometimes I think jeez they think a lot like me.. There is black there is white... there is no grey. They use people to their own ends, they respond in the way they that they suspect others would expect them to respond.. That is why on occassions, people with autism do scare the horses, their respones, to US seem inappropriate. Because they don't know the appropriate response (from society's point of view that is) and respond in an unusual way at times.

People who have no close contact with autistic or Aspergous syndrome people, really have no clue as to how they operate, and are unsettled by them.. People with full on Autism can be a handful, but they are not stupid, they are VERY HIGHLY focussed individuals, to the point of being single minded about a subject that interests them... the worst part of full on autism (to my way of thinking) is the apparent lack of ability to truly love.. they may mouth the words, but words are all they are..(I am sure some of us have said I love you to someone to placate them or to geet em into bed.. I know I have )they view that as a silly thing to waste time on.. and it is hard on my partner knowing her son goes through the motions of loving her, but is incapable of it.. it's not his fault, that is the way he is and we accept him for who he is.. we just wish society would....

Some here could be well advised to do the same :)

[KennyVictor]

.......we accept him for who he is....... Some here could be well advised to do the same :)So, as someone who doesn't know much about autism, let me be a little politically incorrect here and play devils advocate.

How do we know, on a forum such as this, whether someone is single minded because of some medically recognised syndrome or just because they are an obstinate SOB trying to stir people up. (There is more than one person on here who is probably more single minded than is socially acceptable.) And should we treat them differently if we did know?
I like to think I take people for what they are and treat them accordingly. If someone is a pain in the ar se they should be treated as a p.i.t.a. If they are 'normal' treat them in that way because they deserve it, if they have some syndrome - well, how else are they going to learn to fit in?

There, that should win me some friends - not.

KV's alter ego.

[xptdriver]

So, as someone who doesn't know much about autism, let me be a little politically incorrect here and play devils advocate.

How do we know, on a forum such as this, whether someone is single minded because of some medically recognised syndrome or just because they are an obstinate SOB trying to stir people up. (There is more than one person on here who is probably more single minded than is socially acceptable.) And should we treat them differently if we did know?
I like to think I take people for what they are and treat them accordingly. If someone is a pain in the ar se they should be treated as a p.i.t.a. If they are 'normal' treat them in that way because they deserve it, if they have some syndrome - well, how else are they going to learn to fit in?

There, that should win me some friends - not.

KV's alter ego.

Gday Kenny

I guess I take people at their word on matters such as this. If the truth be known there are probably a lot of non diagnosed autistics running around the place. They are very clever at hiding their "disability" for want of a better word. We think of them as not normal whereas they see us. the non autistic as overemotional and bogged down with feelings, feelings that autistics can't get their heads around... They can play act... but that is all that it is.

AS for fitting in? Why should they? They are individuals like the rest of us. They just think and behave a bit oddly at times (according to our norms) and deserve be given a fair go.

[crash]

So, as someone who doesn't know much about autism, let me be a little politically incorrect here and play devils advocate......snip

....I like to think I take people for what they are and treat them accordingly. If someone is a pain in the ar se they should be treated as a p.i.t.a. If they are 'normal' treat them in that way because they deserve it, if they have some syndrome - well, how else are they going to learn to fit in?

There, that should win me some friends - not.

KV's alter ego.

Here is a surprise. I agree with most of the above [the rest was a personal value judgment that others may agree with or may not [depending on who you were talking about:-)]. For the rest of it, in the end, we sink or swim unless obviously seriously handicapped and then you won't find them on any forum.

Aspergerger's or Aspie's for short [I have corrected my original typo spelling mistake I was too late to edit] learn coping skills very quickly. Their big problem is difficulty learning anything they are not especially interested in. In other words, general learning problems even though they often are highly intelligent. Sounds illogical but heck, 'illogical' describes half of life and half of human history.

Espies are at the small end of Autism spectrum disorders and believe me, Wrong Planet Net.com is full of troubled youth more than genuine espie's. There there too, but mostly are the older members. Easy for me to spot the difference in a second. Autism wasn't even known about until not that long ago. I wasn't diagnosed with asperger's until 10 years ago and only after a slip-up from my mother's sister about visits to a Collins st. child psychologist when I was very young and then through visits to one myself after I had found that out. Explained why I had spent my whole youth as a misunderstood loner and unliked mostly. I was terrified of everyone, I thought [I really did] come from another planet. People, especially kids pick up that something is different, they fear that and people avoid what they fear [kill if it was allowed]. Normal human response.

We are not single minded except in extremely rare cases and they make it into the newspapers or docco's [obsessions with train timetables etc,] but we do tend to get into intense detail [handy for punting] and obsession with any subject or hobby we become interested in [I've had many], to the point that would physically exhaust anyone else while we are just cruising happily along. Can be very disturbing for someone living with you. Unusual traits and skills are par for the course and ditto lack of them. I can't remember numbers or letters unless I write them down, It is not uncommon for me to take up to 5yrs. to remember my phone number, pin. number or rego. number, yet because I went through an obsession with history at one stage, I can quote dates, times, places and obscure facts like a machine in any area of history I was interested in. Weird ah ? Anyone ever noticed how many times I edit some of my posts changing one word here or there? Another weird obsessive trait. Thank heaven there is now an editing time limit !!!

No problems with love [I've been married 3 times through good old fashioned love]. Seriously Autistic [or any other well known disorder] people though are rare as hens teeth and movies make it look far worse than it is. Ditto with docco's. They both portray worst case scenarios because it sells. Anyhow, not the place to say more. My original post about it was after a booze-up. I was horrified when I got up realizing what I had said and that I wouldn't be able to edit it out. There are sites available to anyone interested in Autism futher.

What disturbs me though is it is becoming a bit fashionable to have a 'gifted'
aspie child or to use the fact their kid is just a little f.... brat to claim 'he must be autistic' [and deserves special treatment and 'consideration' ..... puke!]. I'd like those parent to experience the real deal themselves for 24hrs. without the coping skills. See how ****** trendy it is after that !!

Cheers and if anyone treats me with any 'special' consideration now, I will just have to track you down and kill you:-)

[crash]

XPT

Your post is EXACTLY spot on and how it is for most of us. We hide it and through abnormal ability to concentrate on anything we are interested in, become experts at it. Guess what the first thing is that we [all] become obsessively interested in? Hiding it !!! :-)

I slipped up here because of a booze-up.

PS. the case of your friend's child is a rare case of advanced Autism [not an aspie], who is going to be a burden on the parents for the rest of their life [no fun for the kid either]. A tragedy.

[crash]

I should clarify something quickly. Where I said: 'the ability to concentrate' [abnormally] ,doesn't mean that anything I get into [abnormally] I always become good at. I don't. Just if I have also a natural talent in that area too.

Punting : average. Painting 5ys. [even though a bit colour blind] Hopeless, Guitar: Ditto for the effort and years. ect. Some great others not so great. not even if I'm hopeless, I still keep going at it like a rabbit and know I'm hopeless, but can't stop until it runs it's course. Sometimes years, sometimes weeks.

[jfc]

At the risk of being seen as a bad loser (or looser in some circles) I consider this a badly worded question. Just the sort of question a study of statistics is likely to engender as we all know statisticians like their figures to mean what the statistician wants them to mean.

Scenario 1. A family has two children and one of them is a girl therefore it is logical to assume one of them isn't. I mean how many non statisticians would say "I have two children, one is a girl and the other is a girl."
So: Answer to the original question 100%

Scenario 2. We see a picture of the unfortunate statisticians children, they aren't attractive, in fact you can't tell what sex they are with their clothes on. The statistician points to one and says 'She is a girl'. What's the other one then we wonder and of course the answer is 50/50 it's a boy since it's a even chance either way.
So: Answer to the original question 50%

The 66% scenario is more of a play on words than a sensible question.

Well, someones gotta be controversial. Crash has dissappeared and P57 has a fortnight in the sin bin.

KV

The important thing in this exercise was that some people should realise they have gaps in their basic probability skills and try to take steps to remedy them, and thus save themselves fiscal grief.

But you cannot resist playing the fool to dumb down this resource even further.

I wonder how much the management appreciate this when they are trying to use this forum to market intelligent rating systems based on mathematical modelling.

As far as I can see Woof's presentation of a classical probability puzzle is correct.


You are told that a family has two children. You are also told that one of those two children is a girl.



It is wrong to infer that a parent of the kids told you this.

It is wrong to infer that you were shown a picture of them.

It is also wrong to infer as CP later did, that the firstborn was a girl (or in his argument "a heads").

And it is beneath contempt to try to sabotage a philanthropic effort just because your feathers are ruffled.

As it is wrong for Iomaca to commend both of you in your recalcitrance.

Informing me that he once regularly mentally calculated Harmonic Means does not impress me in the slightest. Aiding and abetting such an orgy of ignorance depresses me considerably.

[lomaca]

Informing me that he once regularly mentally calculated Harmonic Means does not impress me in the slightest. Aiding and abetting such an orgy of ignorance depresses me considerably.
JFC!
Sadly, I have to inform you that I am not smart enough to calculate the harmonic mean for more than 3 numbers mentally. (I can't keep the results in memory) You must be younger than I thought, otherwise you would know, that there were books of tables for just about anything. We used those to get the numbers.
Disagreeing with someone, does not mean dismissing other's ideas! At least, it should not be.
And please calm down. We are not at war with each other.
All the best to you.

[slowman]

one is too many and a thousand is not enough,perhaps thats why slowmoe does'nt drink.........

[PullTheWhip]

I think the chance of it being a boy is 2/3.

[OM SHARNTEE]

GREETINGS
Interesting that a MIND game question, can lead to such an opening of HEARTS.

It's obvious that WOOF is not much of a "punter" because he's ----

ASKED A -- "QUINELLA QUESTION" & EXPECTED AN -- "EXACTA ANSWER"