Bisa {VGAM} | R Documentation |
Density, distribution function, and random generation for the Birnbaum-Saunders distribution.
dbisa(x, shape, scale=1, log=FALSE) pbisa(q, shape, scale=1) qbisa(p, shape, scale=1) rbisa(n, shape, scale=1)
x, q |
vector of quantiles. |
p |
vector of probabilities. |
n |
number of observations. Must be a positive integer of length 1. |
shape, scale |
the (positive) shape and scale parameters.
|
log |
Logical.
If TRUE then the logarithm of the density is returned.
|
The Birnbaum-Saunders distribution
is a distribution which is used in survival analysis.
See bisa
, the VGAM family function
for estimating the parameters,
for more details.
dbisa
gives the density,
pbisa
gives the distribution function, and
qbisa
gives the quantile function, and
rbisa
generates random deviates.
T. W. Yee
bisa
.
## Not run: x = seq(0, 6, len=400) plot(x, dbisa(x, shape=1), type="l", col="blue", ylab="Density", lwd=2, main="X ~ Birnbaum-Saunders(shape, scale=1)", ylim=c(0,1.3), lty=3) lines(x, dbisa(x, shape=2), col="red", lty=2, lwd=2) lines(x, dbisa(x, shape=0.5), col="green", lty=1, lwd=2) legend(x=3, y=0.9, legend=paste("shape =",c(0.5,1,2)), col=c("green","blue","red"), lty=1:3, lwd=2) shape = 1 x = seq(0.0, 4, len=401) plot(x, dbisa(x, shape=shape), type="l", col="blue", las=1, ylab="", main="Blue is density, red is cumulative distribution function", sub="Purple lines are the 10,20,...,90 percentiles", ylim=0:1) abline(h=0, col="blue", lty=2) lines(x, pbisa(x, shape=shape), col="red") probs = seq(0.1, 0.9, by=0.1) Q = qbisa(probs, shape=shape) lines(Q, dbisa(Q, shape=shape), col="purple", lty=3, type="h") pbisa(Q, shape=shape) - probs # Should be all zero abline(h=probs, col="purple", lty=3) lines(Q, pbisa(Q, shape), col="purple", lty=3, type="h") ## End(Not run)