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# Questions tagged [random-variables]

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249 views

### On first and last zeros before t in a Brownian Motion

Suppose we have the following random variables, given a fixed $t$ we define the last zero before $t$ and the first zero after $t$: \begin{align*} \alpha_t &= \sup\left\{ s\leq t: B(s) = 0 \...
201 views

### Given $\mathbb{E}[X]$, $\mathbb{E}[\max(0,X)]$, and $\mathbb{E}[\min(0,X)]$, what is $\mathbb{E}[f(X)]$

Let $X$ be any random variable with any distribution. Given that we know $\mathbb{E}[X]$, $\mathbb{E}[\max(0,X)]$, and $\mathbb{E}[\min(0,X)]$, can you write a formula for $\mathbb{E}[f(X)]$ where $f$ ...
1 vote
61 views

### Sharpe ratio and uniformly distributed random portfolio

I am currently working on this paper which derives the Sharpe ratio distribution of uniformly random porfolios: https://www.researchgate.net/publication/...
196 views

219 views

### Are mean-variance efficient portfolio weights random variables with probability distributions?

The mean-variance model outputs a portfolio weight vector whose elements are individual asset weights that sum to 1. Regardless of which portfolio along the efficient frontier is being solved, the ...
1 vote
85 views

### Full Copula View using Meucci's Full Flexible View

I'm currently setting up an "Investment Framework" that should allow the following steps: Investment Committee (IC) has to decide on probabilities for 4 different market states. I have historical ...
1 vote
125 views

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### Tools to measure the randomness of database

I was working on historical data looking for anomalous patterns that we would not expect to occur at random. I'd like to create a scheme to analyze data and markets to test for statistical ...
164 views

### Is there a stochastic equation which can model returns according to its four moments?

The normal stochastic equation only models mean and standard deviation. For now, I'm randomly picking returns from a historical CDF of the returns. I'd like to have some flexibility when it comes to ...
6k views

### Box-Muller Method Proof

Here we want to show that the Box-Muller method generates a pair of independent standard Gaussian random variables. But I don't understand why we use the determinant? For me when you have two ...
9k views

### How to simulate a jump-diffusion process?

I would like to price Asian and Digital options under Merton's jump-diffusion model. To that end, I will have to simulate from a jump diffusion process. In general, the stock price process is given ...
73 views

### Expected number of days inside a corridor

Is there a simple (ish) approximation for the expected number of steps a random walk is within a set of bounds over a given time period? - in particular if i presume log normal and constant vol. If i ...
1 vote
167 views

### GARCH model why we take assumption that returns arei.i.d. random variable? [closed]

In GARCH model why we take assumption that returns are i.i.d.?how can we explain it to a layman?
4k views

### How to use Halton sequence in monte carlo simulation

Does anybody know how to use the Halton pseudo random technique in monte carlo simulation. I'm able to generate the sequences and I know they are correct. I checked a couple of numbers from different ...
368 views

### (Re) normalisation of random variable in Monte-Carlo simulations

I have a very simple model (CIR) with a very simple discretisation scheme (Euler) and I use it to do Monte-Carlo Simulations. It is working. Someone insisted that renormalization of my random ...
1 vote
263 views

### Effects of random-generator-choice on derivative's price

There is a plethora of pseudo-random-generators out there. Some of them are definetly better and some of them severily underperform. My standard tool is Mersenne Twister - when I need to generate ...
345 views

### Are there any standard techniques for adding realistic synthetic microstructure noise to a price series?

This may seem like a strange question, but for my particular application we need to actually add synthetic microstructure noise to real time charts. The signal should still be representative of the ...
3k views

### How to generate a random price series with a specified range and correlation with an actual price?

I want to generate a mock price series. I want it to be within a certain range and have a defined correlation with the original price series. If I choose, say, oil, I want as many time series which ...
5k views

### How can I compare distributions using only mean and standard deviation?

I only have means and standard deviations of samples of two random variables. What technique can I use to determine how similar the distributions these describe are? Assume that the values are built ...
4k views

### Why doesn't Black-Scholes work in discrete time?

I have a question considering Financial markets in discrete Time. One of the main theorems in discrete time is the following. In finite discrete Time with trading times t={1,...,T} the following are ...
A simple interest rate model in discrete time is the autoregressive model, $$I_{n+1} = \alpha I_n+w_n$$ where $\alpha\in [0,1)$ and $w_n\geq 0$ are i.i.d. random variables. When working with ruin ...