F Distribution
Definition
The pdf for theFdistribution is
where Γ( · ) is the Gamma function.
Background
TheFdistribution has a natural relationship with the chi-square distribution. Ifχ1andχ2are both chi-square withν1andν2degrees of freedom respectively, then the statisticFbelow isF-distributed.
The two parameters,ν1andν2, are the numerator and denominator degrees of freedom. That is,ν1andν2are the number of independent pieces of information used to calculateχ1andχ2,respectively.
Examples
Compute theFDistribution pdf
Compute the pdf of anFdistribution with 5 numerator degrees of freedom and 3 denominator degrees of freedom.
x = 0:0.01:10; y = fpdf(x,5,3);
Plot the pdf.
figure; plot(x,y)
The plot shows that theFdistribution exists on positive real numbers and is skewed to the right.
See Also
fcdf
|fpdf
|finv
|fstat
|frnd
|random