# Questions tagged [partial-moments]

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### Integral of a CDF

I'm solving a problem where I've this 'expectation': $$\int_{0}^y x\cdot f(x) dx$$ where $f(x)$ is a PDF with support on $[0, z]$, with $z>y$. Is there a way to rewrite it without the integral ...
285 views

### What is the derivation for "Partial Expectation"?

On the Wikipedia page for Log-normal distribution It is written that $$E[X|X>k]Pr(X>k)=\int_{k}^{\infty}xf_{X}(x)dx$$ I know it is probably simple, but I am still wondering the derivation. Since ...
2k views

### What should the integral of a CDF be called?

This is strictly a nomenclature question. I have no particular problem finding double integrals of the type $\int\int\text{pdf}(y) \, d y \,d x$, and I find them quite useful. Whereas we have a good ...
37 views

### Expected value of a random variable with truncation

Let $f:[0,\infty)\to \mathbb R_+$ denote the PDF of a random variable $X$ and $c>0$ a constant. I want to evaluate the following integral: $$I(c)=\int_0^\infty{\min(x,c)f(x)dx}.$$ This can be ...
39k views

### What is the difference between finite and infinite variance

What is the difference between finite and infinite variance ? My stats knowledge is rather basic; Wikipedia / Google wasn't much help here.
83 views

### Is there a phrase for to describe $xf(x)$ where $f(\cdot)$ is the probability mass function?

We know that $\mathbb{E}[X] = \sum_x xf_{X}(x)$ where $f_X(\cdot)$ is the probability mass function. Is there any phrase that we use to describe $\sum_{x\le a} xf_X(x)$, or is there any phrase that we ...
11k views

### How does saddlepoint approximation work?

How does saddlepoint approximation work? What sort of problem is it good for? (Feel free to use a particular example or examples by way of illustration) Are there any drawbacks, difficulties, things ...
1k views

### When would we use tantiles and the medial, rather than quantiles and the median?

I can't find definitions for either tantile or medial on Wikipedia or Wolfram Mathworld, but the following explanation is given in Bílková, D. and Mala, I. (2012), "Application of the L-moment method ...
70 views

### Measures of central tendency for right-skewed size distributions

Suppose we are looking at a right-skewed size distribution such as the distributions of income, casualty losses, or flood sizes, and we want to look at some alternative measures to jointly represent ...