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This is a very well written blog, and the links to pdfs providing further detail are excellent.

As pointed out in jane.pdf, and also be Ed Thorp elsewhere, betting with the Kelly criterion requires large amounts of capital. The reason is simple; there is a real chance of going broke if you start out near 0. This can be countered by playing a fractional Kelly strategy, where you bet Kelly, but only on a fraction of your bankroll.


The smartest man in the room is a fool if he makes others look foolish.

-Ancient Chinese proverb


Source? I can't find it on Google.


Probably ancient China.


The answers on HN are better and have more variety than SE!


This journal is going under:

http://daviddobbs.posterous.com/journal-of-cosmology-going-o...

From Reddit:

http://www.reddit.com/r/science/comments/fy4w5/journal_of_co...

I think it is safe to ignore articles published in this journal.


Most studies use raw p-values. This, coupled with "exploratory analyses" which are not mentioned in the research, leads to a high false discovery rate.

Alternatives include using simulations to estimate false discovery rates (this can be done analytically for some problems). Bayesian frameworks can also be applied, depending on the amount and accuracy of prior knowledge of the system under study.

That said, I see nothing wrong with publishing results with nominal p-values, as long as the researchers indicate the weakness in their results. Meta-analyses can always come back later and use the results they publish.

What annoys me is seeing 50 or so statistical tests done, and then researchers stating they have found something when 1 of those tests shows a p-value of 0.05. Just using a Bonferroni correction, the simplest of all corrections, would demonstrate that findings like this are not significant.


This is similar to other models of courtship behavior. Essentially, females prefer males that invest in their relationship because they are more likely to remain in the relationship. This same phenomenon can be found in all sorts of things, such as law offices (why are they so fancy?!).

A great general model on this can be found here (pdf): http://octavia.zoology.washington.edu/publications/forthcomi...

This is a chapter from a book (P. Zak, ed. Moral Markets: The Critical Role of Values in the Economy. Princeton University Press).


I agree, this math is terrible. Just. Terrible.

Please no one believe this post, it uses dubious statistics.


it depends on your assumptions. i updated some of the numbers, but if you have suggestions definitely feel free to add a comment.


Sorry to be so harsh, but this analysis is really lacking.

If you want to learn more about how to hedge bets, read about things like moment theory or the Kelly criterion.

Also, taking a measure like variance would be much more meaningful than just the spread of the payoff.


Thank you much for crafting this finely worded commentary!!! One point to add:

Many economists assume equilibrium in their models. Often, economists will invoke [Nash] equilibrium as the resting state of the economy. This simplifies their maths, but seems like a dubious assumption for most real world situations. Human activity is biological, and evolving. Economies are complex systems composed of biological entities (humans), and need not ever reach equilibrium.

Out of respect for the recently deceased economics genius, B. Mandelbrot, I urge brave souls to learn his two cents on the topic.


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