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From Ted Dunning <ted.dunn...@gmail.com>
Subject Re: Probability from log likelihood in LDA output
Date Mon, 06 Dec 2010 16:57:20 GMT
Yes.  I should be possible to use exp to get the actual probability.  The
fact that it is a sum
of log probabilities just means that the probability is a product of
probabilities.

It is possible that the probabilities are not normalized, but that would be
a bit surprising for
this kind of algorithm.

On Mon, Dec 6, 2010 at 8:02 AM, Quiroz Hernandez, Andres <
Andres.QuirozHernandez@xerox.com> wrote:

> Hello,
>
> As I understand it, the output for LDA is a log likelihood value for
> each word/topic pair, which is a function of log(P(w|t)). Is it possible
> to invert that function to obtain P(w|t)? I have a feeling it is not,
> since it looks like the final value is obtained as a sum of log
> probabilities, but I just wanted to check, since an output as a
> probability is more readable than the likelihood value given.
>
> Thanks,
>
> Andres
>

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