The F-Ratio Distribution

parameter

r

1

3.

parameter

r

2

6.

mean:	r 2 r 2 -2	=	1.50
variance:	2 2 r 2 ( r 1 + r 2 -2) r 1 ( r 2 -4) 2 ( r 2 -2)	=	5.250

If

U

and

V

are chi-squared random variables with

r

1

and

r

2

degrees of freedom, then the ratio

U/

r

1

V/

r

2

follows the F-ratio (or F-distribution) with parameters

r

1

and

r

2

.

The F-distribution arises in statistical comparisons of the variability in two populations.