Quote:
Originally Posted by funkyj
As the sample size gets bigger your actual results tend to move farther and father from the mean in absolute (e.g. dollars) terms.
E.g. if you WR is +8 bb/100 (a really good WR) but you are very unlucky (your actual performance is always -2 stddevs) then you will win money in the long run but start off a loser.
What does happen is that as the sample size gets bigger and bigger, your win rate (i.e. your +ev decisions) dominates variance more and more.
Quote:
Originally Posted by spadebidder
This is very slightly incorrect, but the difference is critical. The correct statement is, as the sample size gets bigger the average result will tend to be farther and farther from the mean in absolute terms. Not "your actual results".
last I checked "average" in statistics means "mean".
EV is a weighted average i.e. the mean value expected. So actually the average will always be the same as the mean or EV because, by definition they are the same.
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What this means is that the average offset from the mean tends to get bigger, with average here referring to the average sample or average player.
again, from what I've read, when we are talking about normal distributions (or binomial distributions, for which a normal is often a reasonable approximation) we use "standard deviation" to describe the probability distribution of values away from the mean (EV). I'm not sure what this "average offset" you speak of is. A quick googling did not enlighten me.
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It does not mean that a particular player can expect their offset to continue to grow with the sample size. The future expectation for any specific player is that their offset remain exactly where it is right now, forever. Their future random walk is about that point (where they are now) not about absolute zero.
by definition, is is more likely that you will perform closer to your EV rather than farther. OTOH, if you want to do worst case analysis, you typically pick some probabilistic threshold you are comfortable with (e.g. +- 2 stddevs) and base you analysis on that. E.g. the "20 buy-in rule" is based on assumptions about win rates, standard deviations and confidence intervals. It is a fact, that as the sample size gets larger, any fixed confidence interval (e.g. +- 1 stddev) gets bigger. This is what I mean when I say:
Quote:
Originally Posted by funkyj
As the sample size gets bigger your actual results tend to move farther and father from the mean in absolute (e.g. dollars) terms.
i.e. the minimum and maximum of what ever confidence interval you have chosen will grow father and farther apart as the sample size (e.g. number of hands played) grows bigger.
What I'm saying is that the
signal-to-noise ratio improves as the sample size gets bigger which is just another way of saying that, in the long run, WR (a linear function) dominates stddev (a sqrt() function).
Happy nitpicking!