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Nov 10, 2023 at 18:06 comment added Aaron Hendrickson It seems the way to think about this is from the perspective of how the sample space is partitioned. If we define the data reduction $\mathbf X\to L(\theta|\mathbf X)$ with the equivalence relation specifying that samples $\mathbf X$ that produce proportional likelihoods are equivalent then we do indeed get a minimal sufficient partition of the sample space. So while the likelihood is not a statistic in the usual sense, it combined with this equivalence relation serves to induce the same unique partitioning that a minimal sufficient statistic would.
Nov 10, 2023 at 15:42 comment added Iosif Pinelis @MichaelHardy : If the likelihood is defined, as apparently was done in your comment, up to a factor not depending on the parameter, then you do get a minimal sufficient statistic, according to the "useful characterization of minimal sufficiency".
Nov 10, 2023 at 15:27 comment added Michael Hardy mathoverflow.net/questions/140481/what-is-a-likelihood-kernel If we take the "likelihood kernel" to be what I defined it to be in the posting linked here, we then have the question of whether the likelihood kernel is a minimal sufficient statistic.
Nov 10, 2023 at 15:25 comment added Michael Hardy I upvoted your answer.
Nov 10, 2023 at 15:25 comment added Iosif Pinelis @MichaelHardy : Have you just downvoted my answer? If so, why?
Nov 10, 2023 at 15:24 comment added Iosif Pinelis @MichaelHardy : The comment was one under, and concerning, the answer. Do you think that in every comment under the answer I have to repeat the relevant definitions given in the answer?
Nov 10, 2023 at 15:21 comment added Michael Hardy \limits seems to be intended to cause the positioning of subscripts and superscripts in an "inline" setting to behave the way they otherwise would in a "displayed" setting. Since this instance of the use of \operatorname{argmax} was already in a "displayed" setting, \limits would have no effect.
Nov 10, 2023 at 15:06 comment added Michael Hardy $$ \begin{align} & \operatorname{argmax}\limits_{\theta\in\Theta} L_X(\theta) \\ {} \\ & \operatorname*{argmax}_{\theta\in\Theta}L_X(\theta) \end{align} $$ I changed the first form above, coded as \operatorname{argmax}\limits_{\theta\in\Theta} L_X(\theta), to the second, coded as \operatorname*{argmax}_{\theta\in\Theta} L_X(\theta). I'm guessing the use of \limits was intended to affect the position of the subscript, but that didn't work.
Nov 10, 2023 at 14:47 comment added Michael Hardy I didn't mean to say that your answer omits that. Rather, I was responding to your comment about what Aaron Hendrickson said.
Nov 10, 2023 at 14:45 comment added Iosif Pinelis @MichaelHardy : As was explained in my answer, in the context of sufficiency, by "the likelihood function" I mean the statistic $L_X$. This statistic may indeed contain "some information not relevant to estimating" the parameter, in the precise sense that $L_X$ may not be minimal sufficient -- which is what I said in my latter comment.
Nov 10, 2023 at 14:39 comment added Michael Hardy People who write about this don't always say which of those two conventions they have in mind.
Nov 10, 2023 at 14:30 comment added Michael Hardy @IosifPinelis : I wonder whether the truth value of your latest comment depends on what you consider to be the likelihood function. For the example you mention, I might write $$ L(\lambda) \propto e^{-n\lambda} \lambda^{x_1+\cdots + x_n} $$ and say that's the likelihood function. But I imagine some (you?) might write $\text{“} {=} \text{”}$ rather than $\text{“} {\propto} \text{”}$ and include the reciprocal of the product of factorials, in which case the likelihood function would give some information not relevant to estimating $\lambda. \qquad$
Nov 10, 2023 at 14:18 history edited Michael Hardy CC BY-SA 4.0
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Oct 31, 2023 at 21:52 comment added Iosif Pinelis @AaronHendrickson : In general, the likelihood function is not minimal sufficient. E.g., consider the iid sample of size $n\ge2$ from the Poisson distribution with parameter $\theta$.
Oct 31, 2023 at 17:05 comment added Aaron Hendrickson Is the fact that the MLE is always a function of a minimal sufficient statistic a direct consequence of the likelihood function itself being minimal sufficient?
Aug 3, 2023 at 12:57 history edited Iosif Pinelis CC BY-SA 4.0
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Aug 3, 2023 at 10:38 vote accept Aaron Hendrickson
Aug 3, 2023 at 2:23 history edited Iosif Pinelis CC BY-SA 4.0
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Aug 3, 2023 at 2:13 history edited Iosif Pinelis CC BY-SA 4.0
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Aug 2, 2023 at 21:13 history edited Iosif Pinelis CC BY-SA 4.0
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Aug 2, 2023 at 20:57 history edited Iosif Pinelis CC BY-SA 4.0
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Aug 2, 2023 at 20:27 history edited Iosif Pinelis CC BY-SA 4.0
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Aug 2, 2023 at 20:21 history answered Iosif Pinelis CC BY-SA 4.0