est.kappa {CircStats}

Estimate Kappa

Description

Computes the maximum likelihood estimate of kappa, the concentration parameter of a von Mises distribution, given a set of angular measurements.

Usage

est.kappa(x, bias=FALSE)

Arguments

x

vector of circular data measured in radians.

bias

logical parameter determining whether a bias correction is used in the computation of the MLE. Default for bias is FALSE - the bias correction is not used.

Details

Best and Fisher (1981) show that the MLE of kappa is seriously biased when both sample size and mean resultant length are small. They suggest a bias-corrected estimate for kappa when n < 16.

Value

Maximum likelihood estimate of kappa, the concentration parameter of a von Mises distribution, given a set of angular measurements.

References

Jammalamadaka, S. Rao and SenGupta, A. (2001). Topics in Circular Statistics, Section 4.2.1, World Scientific Press, Singapore.

Best, D. and Fisher N. (1981). The bias of the maximum likelihood estimators of the von Mises-Fisher concentration parameters. Communications in Statistics - Simulation and Computation, B10(5), 493-502.

See Also

circ.mean, circ.disp, circ.summary, est.rho

Examples

data <- rvm(15, 0, 3)
est.kappa(data)
est.kappa(data, bias=TRUE)