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Applied and theoretical statistics: e.g. statistical inference, regression, time series, multivariate analysis, data analysis, Markov chain Monte Carlo, design of experiments.
7
votes
Generate Bernoulli vector with given covariance matrix
I'm going to provide two algorithms here:
A super-exponential-time solution that works in all cases.
A polynomial-time solution that applies if the mean values are known and if a certain matrix is p …
2
votes
Accepted
Constructing a Bernoulli random variable for ratio of Bernoulli weights
The obstruction that Bjørn Kjos-Hanssen describes can be made even worse-- it applies to any algorithm (not just von Neumann's trick) and also applies to randomized algorithms (i.e. even if the number …
1
vote
How to sample uniformly from singular matrices
This is an MCMC algorithm for uniform sampling over singular $n$ by $n$ Bernoulli matrices.
Let $H$ (for "hypercube") be the set of all 0/1 vectors of length $n$.
One step of the MCMC algorithm is a …
0
votes
Removing outliers from circular average data
First, in case you haven't run across this before, a classic reference for this area of statistics is Mardia and Jupp's Directional Statistics, which includes a number of measures capturing circular a …
3
votes
How to sample uniformly from singular matrices
[Edit: After improving the rejection sampling algorithm and running it on a more powerful computer, I was able to extend my earlier numerical experiments. Improvements are described below in square b …
2
votes
Accepted
Multinomial transformation for matrices
At the suggestion of the original poster, I am summarizing an alternate answer that has a few strengths relative to my original answer. It is related to the question and answer at this MathOverflow Q …
2
votes
Accepted
Closure of random rotations
Yoav Kallus' comment above is correct; I'm going to sketch a few of the details below for the sake of completeness.
Yoav points out that if we choose $X$ with parameter
$$F=\begin{bmatrix}a&0&0\\0&0& …
2
votes
Multinomial transformation for matrices
(Edited to fix a bug.)
I think the following bijection will do what you want.
For $1\leq i,j\leq n-1$, define
$$r_{ij}=\log(p_{ij}/p_i)$$
Given the $r_{ij}$ and the marginals, we can recover the $p …
1
vote
Accepted
How to perform Importance Sampling with Prior Information
Having explicit bounds on $\mathbb{E}[f(X)]$ does not appear to be useful. The variance can still be arbitrarily large, and the variance governs the rate of convergence for MC sampling. And if the v …
2
votes
Accepted
Tightness of probabilty distributions
I think this conjecture is false, that is, there does not necessarily exist a subsequence that converges to a true probability distribution. Consider the following situation:
Let $Q=(1,0,0,0,...)$, …
1
vote
log-like distance between probability distributions
What about the symmetric-ized KL divergence?
$$D(p,q) + D(q,p)$$
Recalling that
$$D(p,q) = \sum_x p(x) \log \left(\frac{p(x)}{q(x)}\right)$$
then the $\log(p/q)$ is the order of magnitude of the ratio …
2
votes
What's the cumulative probability of these particular bags of liquorice allsorts?
I think the OP is re-inventing Fisher's Exact Test, so perhaps an examination of that may be clarifying.
FWIW, questions like this might be better suited to CrossValidated, which is a StackOverflow si …
1
vote
Strategy optimization based on biased data
I don't understand the specifics of the gateway problem well enough to comment, but on the broader question of "how do I perform inference or optimization when I have observational data, and it's prob …
7
votes
1
answer
291
views
Closure of random rotations
Are matrix Fisher random variables closed under multiplication?
For those unfamiliar with the jargon, let me unpack the terms above and repose my question.
This is a question about probability distrib …
6
votes
1
answer
244
views
Violating an order statistic inequality?
[Edit: for posterity, I'm adding two small comments to the code explaining how to fix it, in light of Iosef Pinelis' answer below. Look for "Should be:" to find the corrections.]
Suppose we draw a sam …