Matrix Differential Calculus with Applications in Statistics and Econometrics, 3rd Edition
by Jan R. Magnus, Heinz Neudecker
Chapter 12Statistical preliminaries
1 INTRODUCTION
The purpose of this chapter is to review briefly those statistical concepts and properties that we shall use in the remainder of this book. No attempt is made to be either exhaustive or rigorous.
It is assumed that the reader is familiar (however vaguely) with the concepts of probability and random variables and has a rudimentary knowledge of Riemann integration. Integrals are necessary in this chapter, but they will not appear in any other chapter of this book.
2 THE CUMULATIVE DISTRIBUTION FUNCTION
If x is a real‐valued random variable, we define the cumulative distribution function F by
Thus, F(ξ) specifies the probability that the random variable x is at most equal to a given number ξ. It is clear that F is nondecreasing and that
Similarly, if (x1, … , xn)′ is an n × 1 vector of real random variables, we define the cumulative distribution function F by
which specifies the probability of the joint occurrence xi ≤ ξi for all i.
3 THE JOINT DENSITY FUNCTION
Let F be the cumulative distribution function of a real‐valued random variable x. If there exists a nonnegative real‐valued (in fact, Lebesgue‐measurable) function f such that ...
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