Date: Mon, 03 Nov 1997 22:12:56 +0100
From: jhorikx <jhorikx@stads.net>
Newsgroups: sci.math.num-analysis
Subject: Re: Statistics

Neal Patel wrote:

> What are marginal and conditional distributions?


Dear mua,

This is not really a question for sci.math.num-analysis isn't it ?  Why
don't you try
sci.stat.edu or sci.stat.math ?  Nevertheless:

Suppose there are 100 students, 60 male (M) and 40 female (F), they
study either astronomy (A) or biology (B) then it would be possible
that:


               M       F           total

A            35      15          50
B            25      25          50

total       60       40

The 50-50 and 60-40 are the marginal distributions, because they
are presented in the margin of the -four number- proper table.
Knowing the marginal distribution you can say that the possibility
that a student (at random !) follows biology equals 50%.

15-25 is an exemple of an conditional distribution. It says: given
the fact (condition) that someone is a female the chance that she
follows astronomy is some 37.5 %  (15/40 ).

kind regards
Jos Horikx