esag.reg: Spherical regression using the ESAG distribution

In Directional: A Collection of Functions for Directional Data Analysis

Spherical regression using the ESAG distribution

Description

Spherical regression using the ESAG distribution.

Usage

esag.reg(y, x, con = TRUE, xnew = NULL, lati = 10, longi = 10, tol = 1e-06)

Arguments

y	A matrix with 3 columns containing the (unit vector) spherical data.
x	The predictor variable(s), they can be continnuous, spherical, categorical or a mix of them.
con	Do you want the constant term in the regression?
xnew	If you have new data use it, otherwise leave it NULL.
lati	A positive number determing the range of degrees to move left and right from the latitude center. This number and the next determine the grid of points to search for the Q matrix described in Paine et al. (2020).
longi	A positive number determing the range of degrees to move up and down from the longitude center. This number and the previous determine the grid of points to search for the Q matrix described in Paine et al. (2020).
tol	A tolerance value to decide when to stop the successive optimizations.

Details

The second parametrization of the ESAG regression (Paine et al., 2020) is applied.

Value

A list including:

loglik	The log-likelihood of the regression model.
param	A vector with three numbers. A measure of fit of the estimated values, defined as \sum_{i=1}^ny_i^T\hat{y}_i. This appears if the argument "xnew" is NULL. The \rho \in (0,1] (smallest eigenvalue of the covariance matrix)), and the angle of rotation psi.
gam	The two \gamma parameters.
beta	The beta coefficients.
seb	The standard error of the beta coefficients.
est	The fitted values of xnew if "xnew" is NULL. If it is not NULL, the fitted values for the "xnew" you supplied will be returned.

Author(s)

Michail Tsagris.

R implementation and documentation: Michail Tsagris [e-mail].

References

P. J. Paine, S. P. Preston, M. Tsagris and Andrew T. A. Wood (2020). Spherical regression models with general covariates and anisotropic errors. Statistics and Computing, 30(1): 153–165. https://link.springer.com/content/pdf/10.1007

See Also

esag.mle, iag.reg, spml.reg

Examples

y <- resag( 25, rnorm(3), c(1, 1) )
## this is a small example to pass CRAN's check because the default argument values
## of lati and longi require many seconds
a <- esag.reg(y, iris[1:25, 4], lati = 2, longi = 2)

Directional documentation built on Oct. 30, 2024, 9:15 a.m.