Talk:Dirichlet distribution

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Should that be a Dirac delta, not a Kronecker delta? If it were Kronecker, then distribution would be everywhere finite, but nonzero only on a set of measure zero.

According to David J.C. MacKay and Linda C. Bauman Peto "A Hierarchical Dirichlet Language Model" it should be a Dirac delta function.

It is clearly a Dirac delta since it has to be defined over real numbers, and not integers.


[edit] Question regarding chained Dirichlet distributions

If I draw a probability distribution X\sim Dir(\alpha), and then another distribution Y\sim Dir(rX) for some constant r, is the marginal distribution of Y Dirichlet? A5 15:12, 20 April 2006 (UTC)

[edit] Dummy questions

I think, the sum which is 1 in the second paragraph should sum over all Alphas not over all x. Munibert 16:29, 15 March 2007 (UTC) Am I right or wrong?

Since, I now realise that the Alphas stand for events (from N) and the x are the probabilities I was wrong. But why does one use this terminology which seems to reverse the usage from multinominal distributions? Munibert 16:35, 15 March 2007 (UTC)

Can someone please explain what this distribution reflects? For the normal distribution, the authors go into lengths to cite examples what kinds of everyday values follow a normal distribution... cannot someone add an example like this for the dirichlet distribution? --Maximilianh 05:18, 4 June 2006 (UTC)

The "cutting up strings" text recently added provides a minimal example of where this distribution would come up. Having others would be good, of course. BSVulturis 20:47, 12 March 2007 (UTC)

Why is this distribution called a continuous distribution, when the cumulative distribution is not continuous? It should be neither continuous nor discrete. Albmont 18:58, 16 October 2006 (UTC)

It's now defined without the dirac delta function that was there before. Someone will have to check, but I think it's now defined over a set that we integrate and whose integral is continous. MisterSheik 21:36, 27 February 2007 (UTC)

What does this mean? "The characteristic function χ ensures that the density is zero unless..." The page doesn't define a characteristic function. I'm going to change it to say that the sum over the x's is defined as 1, which is what I think it means... MisterSheik 20:05, 26 February 2007 (UTC)

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