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Apr 5, 2015 at 15:17 vote accept Simd
Mar 29, 2015 at 18:18 history bounty ended Simd
Mar 24, 2015 at 13:39 comment added Will Sawin I think it's $1/m$, just like the answer for $2$ moments, because you can cancel the contribution of $N_m=0$ to the skewness by slightly adjusting the probability that $N_m$ is large, while not affecting the variance very much. The next question is whether you can choose dependencies of the $N_m$s such that the intermediate moments are OK.
Mar 24, 2015 at 13:36 comment added Will Sawin @dorothy I think that one has a constant expected minimum. I think getting a nonconstant expected minimum, if possible, requires a distribution that does not treat $1$ to $n$ symmetrically. A related question: If $N_m$ is a random variable valued in $\mathbb N$ whose first three moments are the same as a Poisson variable with mean $m$, what is the largest possible value of $P(N_m=0)$?
Mar 23, 2015 at 10:53 comment added Simd Thank you! I don't know if it is helpful but Douglas Zare gave a very nice $3$-wise independent process at mathoverflow.net/a/102214/48334 previously. It was interesting as it showed that in that case $4$-wise independence really was necessary.
Mar 22, 2015 at 20:36 history answered Will Sawin CC BY-SA 3.0