shapeparameter: Shapeparameters of a beta-distribution from the mean, the...

In carcass: Estimation of the Number of Fatalities from Carcass Searches

Shapeparameters of a beta-distribution from the mean, the lower and upper limit of the 95% confidence or credible interval

Description

The function returens the shapeparameters a ad b of a beta-distribution from the mean, the lower and upper limit of the 95% confidence or credible interval. The derivation from mean and se to the shapeparameters of a beta-distribution is done by the method of moments.

Usage

shapeparameter(m, lwr=NA, upr=NA, se=NA)

Arguments

m	mean
lwr	lower limit of the 95percent confidence/credible interval
upr	upper limit of the 95percent confidence/credible interval
se	standard error of the proportion

Details

Either se or both lwr and upr has to be given. The result may be more reliable if se is given, since the calculation is based on se. If the lwr and upr limits of the 95% confidence interval are given, se is estimated as 1/4 times the width of the 95% confidence interval.

Value

a	parameter a of a beta-distribution
b	parameter b of a beta-distribution

Author(s)

Fraenzi Korner-Nievergelt

References

Gelman et al. (2004)

Examples

a <- shapeparameter(0.8, 0.72, 0.88)$a
b <- shapeparameter(0.8, 0.72, 0.88)$b
x <- seq(0, 1, by=0.01)
y <- dbeta(x, a, b)
plot(x, y, type="l")

carcass documentation built on Oct. 3, 2023, 9:08 a.m.