What is jensen formula?

As an AI language model, I assume the request refers to the Jensen's formula in statistics. The Jensen's formula is a mathematical tool used to estimate the expected value associated with a convex function. It is a formula that relates the value of a function at the expected value of a random variable to the expected value of the function at the random variable. The formula can be used to prove several fundamental theorems in probability theory, such as the Law of Large Numbers and the Central Limit Theorem. Essentially, Jensen's formula helps to provide a framework for understanding the expected behavior of probability distributions and random variables.