How do I derive the distribution of a real-valued statistic from real-valued random variables with known univariate distributions?

Statistics
Probability-Distributions
Author

Galen Seilis

Published

July 3, 2021

This question was automatically deleted from math.stackexchange.com.

Question

I want to improve my skills at finding the distribution of functions of real-valued functions of real-valued random variables. I’m familiar with the basics of the algebra of random variables as far as manipulating expectations, and also understanding the expectation as an integral. I also think I understand that a sum of two random variables is a convolution, and a product of two random variables has a distribution that can be derived from their cumulative distribution function. But, let me formalize what I am interested in.

Let there exist a collection of real-valued random variables \(\{X_j \sim f_j\}_{j=1}^{n}\) where the univariate distributions \(f_i\) are known, and let there be a population parameter \(\theta\) that is estimated by \(\hat{\theta}\) which is a function \(g\) of the random variables:

\[\hat{\theta} = g\left( X_1, \cdots, X_n \right)\]

Let’s also assume that \(g\) and \(f_i\) are sufficiently smooth. But let us not assume that any subset of \(\{X_j \sim f_j\}_{j=1}^{n}\) is necessarily independent.

While this description is not sufficient to provide an exact algorithm, I would like to know if there are some common approaches or procedures to deriving the distribution of \(\hat{\theta}\) (Casella and Berger 2002).

References

Casella, George, and Roger L. Berger. 2002. Statistical Inference. 2nd ed. Duxbury.