Yeah, it didn't help that his numbers didn't add up to 100. Sherman, I took the liberty of fixing your post (A wins 70 and B wins 30, not A wins 70 and B wins 70).

That is what I meant to type, so I am glad you fixed it.

Oops! Hope you didn't bet too much!
Think critically about everything you read and hear. Especially question a claim made about something not in the author's area of expertise (I wouldn't go to a psychologist to learn about mathematics, nor to a mathematician to cure my craziness). But I think Monteroy's explanation is likely, and you didn't read carefully enough. Maybe you only saw the data and only thought of 1 possible interpretation (which happened to be the wrong one).

I'm a psychologist and people come to me all the time for statistical questions. Statistics and research methods is pretty much a requirement for any BA/BS in psychology in US (exceptions may apply, but I personally would suggest transferring to another university to get a psych degree than to get one without these topics covered). My minor area of study for my Ph.D. was in quantitative psychology. That being said, psychology is much more about applied statistics than about probability theory / mathematics (which no doubt explains my frequent mistakes on this forum about combinations and pure probability problems).

For what it is worth, I doubt this is something that was read in a psychology class. I think the most likely explanation is that either 1) the student remembered what the instructor said incorrectly or 2) the instructor got it wrong. The reason for this that most students don't read (my students always find it amazing when I tell them about a neat study that was in the book; if they were reading they should be bored by it).

Further, despite (research) psychologists have reasonable training in quantitative issues, many of them still suck at it, which makes #1 plausible. #2 is also plausible because...well, see the scores on my exams for the evidence against student memory. I'd rate "didn't read carefully enough" as the third possibility and "book error" as an outside 4th.

So in order of likeliness:
1) Student misheard/misunderstood/misremembered the lecture
2) Instructor said it incorrectly
3) Student misread/misremembered book
4) Book is in error.

My statement wasn't meant as a knock on psychologists' math skills, though it was superfluous to my point. We should question a math claim made by a mathematician just as much as we should question one from a psychologist. I was just saying that if we're gonna be lazy about our critical thinking, we should spend more effort questioning a cross-field claim in general. But I guess the roulette example isn't really cross-field because there is a lot of statistics in psychology as you've pointed out.

This is possibly something to do with confusion surrounding this now widely debunked study.

It could also be to do with the fact that players chasing their losses at roulette tend to move from predictable outside bets (eg most players stick to black or even etc) to unpredictable inside ones (where they just splash the chips everywhere around certain numbers).

This creates a vague correlation in casino data between a higher hourly loss rate and unpredictability in betting patterns, although I doubt this would have made it into much of the general psychology literature.

This 'extra' loss also simply comes from a higher average stake when people are steaming, a higher average stake which happens to coincide with a general change in betting style, not any other strange factor.

This is a classic argument in my opinion and I always like to bring up this point;
Lets say we were flipping a coin ten times.
For the first five flips to our surprise comes heads.
Now for the following flips ; 6,7,8,9,and finally 10.
Probability says the results are individual but theoretically if I bet
3x on tails the 6th bet , 9x on tails the seventh bet, and increasing the bet size(12x,25x,65x) on
tails each time heads wins; I should come out ahead.
(also we decided not to bet on the first five flips.)

No, Martingale-type betting (or any other type) does not change the expectation of the game, your point is false.

Good god you will get crushed. Yes, most of the time you will win a small amount. But you WILL hit a long enough streak (and much sooner than you probably think) in which you will lose more than you can pay. As NewOldGuy says, look up Martingale on wikipedia.

I'm quite sure you are "wrong" about the outcome of this bet. It is the girlfriend that wins. In bets between boyfriend/girlfriend or husband/wife, the normal EV equations do not apply. The believe following scenario illustrates the real situation accurately:

If a man expresses his opinion in the middle of the forest and no woman is around to hear it, would he still be wrong?

it would be very hard to flip a coin ten times and for it to come tails 10 times is what im trying to say.

But you only described betting on five times. The five that came before you began betting have zero relevance. If you had 50 in a row before you began betting it still has zero relevance assuming a fair coin toss. The coin has no memory.

Five tails in a row starting right now has a probability of over 3%.

But that isn't really even the important point. It's that your expectation on such a bet is still zero, as it is for any series of bets on coin flips no matter how you double your bets.

What you are describing is called the Gambler's Fallacy. It's the reason casinos put up that display of past numbers hit on roulette. To encourage betting on a fallacy.

lol

But you fail to comprehend what im trying to say; If you were to flip a coin ten times and it came heads the first 5 times it would be immediately profitable to bet in big increments on tails the following five flips. because probability is no longer individual. The chance of 5tails in a row has over 3% probability, but what about 10 in a row? so next time a new baccarat table opens and banker wins 5 in a row bet player until you win , instantaneous profit.

Surely you know that flipping a coin repeatedly and having it land solely on one side is impossible so probability will just out weigh tails if it came tails 5-10 times in a row never mind this absurd 50times in a row you speak of so lightly.

Nope, I understand clearly, and your statement is absolutely 100% false. Again, this is called the Gambler's Fallacy.


Edit - I'm starting to suspect that you are just pulling my leg and don't actually believe what you are posting.