Probability density function is a statistical expression defining the likelihood of a series of outcomes for a continuous variable, such as a stock or ETF return.

It will be observed that the distribution of y1, y2, ⋯, yn must be such that the joint probability density for y1, y2, ⋯, yn is a function of x2 1 + x2 2 + ⋯ + x2 n, and this condition implies the ...