Questions tagged [extreme-value]
Extreme values are the largest or the smallest observations in a sample; e.g., the sample minimum (the first order statistic) and the sample maximum (the n-th order statistic). Associated with extreme values are asymptotic *extreme value distributions.*
615 questions
10 votes
1 answer
341 views
Distribution of Y conditioned on the index of the minimum of X
Let us consider a pair of random variables $y, x$ with a conditional distribution $p(y | x)$ and marginal distributions $p_Y(y), p_X(x)$. We observe an i.i.d. sample $D_x = \{x_i\}_{i = 1}^n$. The ...
0 votes
0 answers
72 views
Why GPD MLE (EVT) fails to estimate Tail Index for Student T?
Why Generalized Pareto Distribution (GPD) MLE estimation of Tail Index fails? On the chart multiple simulation of the same $\text{StudentT}(\nu=4)$ with tail estimated with GPD estimator (blue lines). ...
0 votes
0 answers
105 views
Parametric bootstrap for a Student-t model when the degrees-of-freedom estimate has a very large standard error
I am analysing a sample of size $n = 200$ that appears to follow a Student-$t$ distribution fixed by design. Fitting the model yields $\hat{\nu} = 10.22$ but with a relatively large standard error of $...
0 votes
0 answers
43 views
Choosing normalizing constants for extreme value distributions for finite samples
There are lots of examples and posts of general rules to find normalizing constants for extreme value theory, see here and there for instance. However, these deal with normalizing to the asymptotic ...
0 votes
0 answers
106 views
Minimum number of observations quantile regression
My goal is to estimate the market beta (so exposure of an asset returns to market shocks) in quantiles : $Q_{r_i|r_M} = a_0(\tau) + \beta_i(\tau)r_M+\varepsilon_i(\tau)$ where $r_i$ are asset returns (...
4 votes
1 answer
109 views
An example of stochastic process $X_t$ on $[0,1]$ such that $\mathbb{E}[\inf_{[0,1]} \left|f(t)\right| X_t] = 0$
What's an example of stochastic process $X_t$ on $[0,1]$(i.e. a random variable for each $t \in [0,1]$) such that For all $t$, $X_t \geq 0$ For all $t$, $\mathbb{E}[X_t] = 1$ $\mathbb{E}[\sup_{t \in [...
1 vote
0 answers
49 views
Classify sample based on min/max values [closed]
Suppose I have a database of entities. The database has a column for the name of the entity, min A, max A, min B, max B. Where the min/max columns are the min/max for variables A and B. It is unknown ...
0 votes
0 answers
64 views
Confidence interval for the size of a population
Let say I want to estimate the number $N$ of balls in an urn by taking a sampling of $n$ balls (without replacement). The balls are numbered from $1$ to $N$ and let $Z$ denote the maximum of the ...
0 votes
0 answers
43 views
Why does GEV fit sometimes not fit the tails well?
I am performing a generalized extreme value analysis using about 20 years of data sampled every 1 minute. I am doing this in order to predict return levels at e.g. 1-in-50 and 1-in-100 intervals. The ...
1 vote
0 answers
73 views
How to get 1-in-100 return period from GEV when using a block length shorter than a year?
I am computing the Generalized Extreme Value distribution for a dataset containing about 15 years of data sampled every 5 seconds. I want to estimate the 1-in-50 or 1-in-100 year return level from the ...
0 votes
0 answers
105 views
Pickands-Balkema-De Haan theorem, Dependence and Shuffling
The Pickands-Balkema-de Haan theorem states that the conditional excess distribution function is well approximated by the generalized Pareto distribution (for high excesses and if the underlying RV's ...
2 votes
1 answer
181 views
Confidence interval for ${θ}/{2}$ in $\text{U}(0, \theta)$
I am trying to find a confidence interval for ${\theta}/{ 2}$ with confidence level $1-\alpha$ (using quantiles at $p_1 = \alpha$ and $p_2 = 1$). So I take unbiased estimator for ${\hat{\theta}}/{2} =...
3 votes
0 answers
94 views
Is there an analytical solution to the distribution of a sum of observations drawn from a Frechet distribution?
Let $X_i$ be an iid draw from a Frechet distribution. Let $\alpha_i \in \mathbb{R}$. Is there an analytical expression of the distribution of $\alpha_1X_1 + \alpha_2X_2 + \alpha_3X_3$? That is, can I ...
1 vote
0 answers
66 views
Convert units, get different results when fitting extreme value distribution with extRemes
I am using the fevd() and lr.test() functions to examine precipitation using the extRemes R ...
2 votes
1 answer
193 views
Expectation of the minimum of random variables (Exponential + Erlang)
Consider the following random variable $$ Z=\min_i\{X_i+Y_i\} $$ for $-n\leq i\leq n$, where $X_i\overset{\mathrm{iid}}{\sim}\text{Exp}(\lambda)$, $Y_i\overset{\mathrm{iid}}{\sim}\text{Erlang}(|i|,\...