# [R]: Noncentral F distribution

Douglas Bates bates at stat.wisc.edu
Mon Feb 14 22:58:19 CET 2000

```Kenneth Cabrera <krcabrer at epm.net.co> writes:

> How can I calculate the Noncentral F distribution?
> I need to calculate the probability of the error type II or the Power of some
> experiment design.

In 0.99.0 the pf function takes an argument ncp, which is the
noncentrality parameter.

FDist                  package:base                  R Documentation

The F Distribution

Description:

Density, distribution function, quantile function and random
generation for the F distribution with `df1' and `df2' degrees of
freedom (and optional non-centrality parameter `ncp').

Usage:

df(x, df1, df2, log = FALSE)
pf(q, df1, df2, ncp=0, lower.tail = TRUE, log.p = FALSE)
qf(p, df1, df2,        lower.tail = TRUE, log.p = FALSE)
rf(n, df1, df2)

Arguments:

x, q: vector of quantiles.

p: vector of probabilities.

n: number of observations to generate.

df1, df2: degrees of freedom.

ncp: non-centrality parameter.

log, log.p: logical; if TRUE, probabilities p are given as log(p).

lower.tail: logical; if TRUE (default), probabilities are P[X <= x],
otherwise, P[X > x].
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```