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In probability and statistics, a probability distribution assigns a probability to each measurable subset of the possible outcomes of a random experiment, survey, or procedure of statistical inference.

2 votes
0 answers
105 views

Distribution of weighted sum of non-central chi-squared r.v.'s: log-concave?

Let $n\geq 2$, and $X_1,\dots,X_n$ be independent non-central r.v.'s, where $X_i \sim \chi^2(\delta_i)$; and $w_1,\dots, w_n > 0$. Letting $$X \stackrel{\rm def}{=} \sum_{i=1}^n w_i X_i$$ is it true …
Clement C.'s user avatar
  • 1,372
12 votes
0 answers
551 views

A measure of non-uniformity of a vector/probability distribution?

In the course of a research project about discrete probability distributions, my coauthors and I keep seeing some quantity appear, and I would like to understand whether it has been studied or has a c …
Clement C.'s user avatar
  • 1,372
5 votes
2 answers
921 views

Subgaussian norm of a symmetric $\{-1,0,1\}$ random variable

Let $p\in [0,1/2]$, and define $\xi$ as the symmetric random variable such that $$ \xi = \begin{cases} 1 & \text{ w.p. } p\\ 0 & \text{ w.p. } 1-2p\\ -1 & \text{ w.p. } p \end{cases} $$ so that $\math …
Clement C.'s user avatar
  • 1,372
3 votes
1 answer
419 views

Inequality on the Hellinger distance between Poisson and mixture of Poisson

Let $H$ denote the Hellinger distance; i.e., for two discrete distributions $p,q$ (identified with their pmf) over $\mathbb{N}$, $$ H(p,q)^2 = \frac{1}{2}\sum_{n=0}^\infty \left(\sqrt{p(n)}-\sqrt{q(n) …
Clement C.'s user avatar
  • 1,372
9 votes
1 answer
460 views

Bounds on the expectation of $|X-Y|$ for $X,Y$ Poisson

I would have a proof of the following fact; but it's a bit clunky, and am wondering if one can get a more elegant one (and/or improve the constants). I couldn't find this anywhere, and searching prope …
Clement C.'s user avatar
  • 1,372
9 votes
3 answers
2k views

Reference on (discrete) log-concave probability distributions

A discrete distribution $p$ over $\mathbb{N}$ is said to be log-concave if it satisfies the following conditions: The support of $p$ is a contiguous interval, i.e. $\exists a \leq b$ s.t. $p_i > 0$ i …
Clement C.'s user avatar
  • 1,372
2 votes
1 answer
306 views

Distribution of a stopped random sum, with subexponential stopping time

I am trying to find a reference (or, if it's false, a counterexample) for the following sort-of-intuitive fact: if $\tau$ is a stopping time with a subexponential probability distribution, and $(X_n)_ …
Clement C.'s user avatar
  • 1,372
2 votes
1 answer
106 views

How to efficiently sample uniformly from the set of $p$-equipartitions of an $n$-set?

I have a question related to this one. For $n,p \in \mathbb{N}_+$ such that $p\mid n$, let $\mathcal{P}^{\rm eq}$ be the set of all equipartitions of $n$ in $p$ sets; i.e., in sets of equal size $\fra …
Clement C.'s user avatar
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