| Geometric {base} | R Documentation |
The Geometric Distribution
Description
These functions provide information about the geometric distribution
with parameter prob. dgeom gives the density, pgeom
gives the distribution function, qgeom gives the quantile
function, and rgeom generates random deviates.
Usage
dgeom(x, prob)
pgeom(q, prob)
qgeom(p, prob)
rgeom(n, prob)
Arguments
x, q |
vector of quantiles representing the number of failures in a sequence of Bernoulli trials before success occurs. |
p |
vector of probabilities. |
n |
number of observations to generate. |
prob |
probability of success in each trial. |
Details
The geometric distribution with prob = p has density
p(x) = p {(1-p)}^{x}
for x = 0, 1, 2, \ldots
If an element of x is not integer, the result of pgeom
is zero, with a warning.
The quantile is left continuous: qgeom(q, prob) is the largest
integer x such that P(X <= x) < q.
See Also
dnbinom for the negative binomial which generalizes
the geometric distribution.
Examples
pp <- sort(c((1:9)/10, 1 - .2^(2:8)))
print(qg <- qgeom(pp, prob = .2))
## test that qgeom is an inverse of pgeom
print(qg1 <- qgeom(pgeom(qg, prob=.2), prob =.2))
all(qg == qg1)
Ni <- rgeom(20, prob = 1/4); table(factor(Ni, 0:max(Ni)))