tweedie_lambda: The Probability of Observing a Zero Value for a Tweedie Density
Description
The probability that the variable takes the value of zero.
Usage
tweedie_lambda(mu, phi, power)
Value
The value of \(\lambda\) when \(1 < p < 2\) such that \(P(Y=0) = \exp(-\lambda)\). When \(p>2\), a vector of zeros is returned.
Arguments
mu
the mean parameter \(\mu\).
phi
the dispersion parameter \(\phi\).
power
the power parameter \(p\) (sometimes denoted \(\xi\)).
References
Dunn, Peter K and Smyth, Gordon K (2005).
Series evaluation of Tweedie exponential dispersion model densities
Statistics and Computing,
15(4). 267--280.
tools:::Rd_expr_doi("10.1007/s11222-005-4070-y")
lambda <- tweedie_lambda(mu = 1:3, phi = 1, power = 1.1)
exp( -lambda)
# When p > 2, there is zero probability that Y = 0:lambda <- tweedie_lambda(mu = 1, phi = 1, power = 3.1)