# Expected value of bivariate pdf

1. May 8, 2009

### boneill3

Is the expected value E[x]or E[y] of a bivariate pdf fXY(xy)

\int x f(x,y)dx

or

E[y]

\int y f(x,y)dy ?

example if f(x,y) = x+y

E[X] = \int x *(x+y)dx

regards
Brendan

2. May 9, 2009

### mathman

You need to carry out the double integral. A single integration gives the conditional expection of one variable with rexpect to the other.

3. May 9, 2009

### boneill3

So just say you had the lmits of 0<x<1 0<y<1
The expected value would be:

regards