Questions tagged [order-statistics]
The order statistics of a sample are the values placed in ascending order. The i-th order statistic of a statistical sample is equal to its i-th smallest value; so the sample minimum is the first order statistic & the sample maximum is the last. Sometimes 'order statistic' is used to mean the whole set of order statistics, i.e. the data values disregarding the sequence in which they occurred. Use also for related quantities such as spacings.
508 questions
3 votes
2 answers
158 views
Probability that the range of a random sample of size $n$ from a continuous distribution includes the population mean?
For the median ($m$), there is a simple formula that it falls within the range of a random sample of size $n$ from a continuous distribution: $$ \mathbb{P}(X_{(1)} \leqslant m \leqslant X_{(n)}) = 2^{...
1 vote
0 answers
149 views
The pdf of $r$-th Order statistics with independent but not identical distribution
I am currently trying to find out the pdf and cdf of the $r$-th order statistic with $X_1,\ldots,X_n$ having the independence but not identical distribution. First I tried it using the usual methods ...
1 vote
0 answers
52 views
Gaussian order statistics
Let $X=(X_1, X_2, \dots, X_n)$ a centered gaussian vector with a positive covariance matrix and $X_{(1)} < X_{(2)} < \dots < X_{(n)}$ his increasing rearrangement. Let $k\in \{2, 3, \dots, n-...
3 votes
1 answer
289 views
Inverse problem of inferring sample distribution from order statistic distribution
It's known that in some cases we can infer distributions on order statistics, given the distributions of samples. (Perhaps relatedly, it's also known that there are cases where we can achieve ...
3 votes
2 answers
365 views
Independent random exponential variables, minus their minimum, are independent (proof?)
I'm taking an inference course via Casella/Berger where students are encouraged to look up "stumper" questions in the online solutions or beyond. (Yes, really.) I'm treating exercise 8.5, ...
5 votes
1 answer
134 views
The first moment of symmetric Dirichlet order statistics
Let $\mathbf q\in[0,1]^n$ be a random vector following a symmetric Dirichlet distribution with parameter $\alpha$: $$ \mathbf{q}\sim \operatorname{Dir}(\alpha,\cdots,\alpha). $$ Define $q_{(i)}$ as ...
1 vote
1 answer
127 views
Distribution of $Z$ = min($y_1, y_2, ... y_n$) $-$ max($x_1, x_2, ... x_n$) [closed]
Given two samples $x_1, x_2, ... x_n$ and $y_1, y_2, ... y_n$, whose values are in [0, 1], what is the distribution of $Z$ = min({$y_1, y_2, ... y_n$}) $-$ max($x_1, x_2, ... x_n$)? It is usually the ...
0 votes
0 answers
113 views
Conditional expectation of order statistics when observing ratio/difference
Suppose two independent ordered draws from some continuous and bounded distribution $F_{[0,\bar{x}]}$ with $f>0$ everywhere, represented by the order statistics $$X_{(1:2)}=\min(X_1,X_2)\text{, and ...
6 votes
1 answer
189 views
What is $\mathbb E[M\times\sum{X_i}]$ in normal distribution, $M$ being the sample median?
Given $X_{1},\ldots,X_{n}$ an iid sample of a standard normal distribution, let $M=M(X_1,\ldots,X_n)$ be the median of this sample. What is the value of$$\mathbb E\left[M(X_1,\ldots,X_n)\times\sum_{i=...
0 votes
0 answers
69 views
What are the alternative summary measures of a maximum order statistic when the expectation of the underlying distribution is not finite?
Suppose, $n$ units are placed on a life test. The time-to-failure follows a continuous probability distribution with non-existing finite moments(like a lower-truncated Cauchy or inverse Lomax). Let, $...
3 votes
1 answer
306 views
Can median or mode of the order statistics be obtained?
Suppose $X_1, X_2,\cdots, X_n$ is a random sample of size $n$ from a continuous probability distribution with cumulative distribution function (CDF) $F(x)$ and probability density function (PDF) $f(x)$...
6 votes
1 answer
161 views
Suppose $Z_i$ are i.i.d. $N(0, 1).$ And let $M_n = \max\{Z_1, \ldots, Z_n\}$, show that $P(M_n > t) \leq n(1 - \Phi(t))$
Show that $P(M_n > t) \leq n(1 - \Phi(t))$ My work: \begin{align} & P(M_n > t) \leq P\left(\bigcup_{i=1}^n (Z_i > t) \right) \\ \leq {} & \sum_{i=1}^n P(Z_i > t)= n(1 - \Phi(t)) \...
5 votes
1 answer
262 views
In a sum of high-variance lognormals, what fraction comes from the first term?
If $X_i \overset{\textrm{iid}}{\sim} \text{Lognormal}(0, \sigma^2)$ for $i=1,\ldots,n$ and $Y_1 = X_1 / \sum_{j=1}^n X_j$, then I would expect that a particular* limiting distribution of $Y_1$, ...
2 votes
1 answer
207 views
Approximation of the expected value of the $i$-th standard normal order statistic in a sample of size n
For random variables $X_1, \cdots, X_n$, we denote the order statistics by \begin{align} X_{(1)} & = \min (X_1,\ldots, X_n) \\[6pt] X_{(2)} & = \text{second-smallest of } X_1,\ldots, X_n \\ &...
3 votes
1 answer
106 views
Rough answer for the maximum of absolute value of $n$ standard gaussians (Computer Age Statistical Inference Problem 1.3)
I am working through "Computer Age Statistical Inference" as a self-study and am stuck on the follow exercise (1.3): The details of equation 1.6 are unimportant for the exercise, so far as ...