spselect (version 0.0.1)

stagewise.ss: Spatial scale incremental forward stagewise regression

Description

This function fits a spatial scale (SS) incremental forward stagewise regression model.

Usage

stagewise.ss(y, X, X.3D, ss, increment, tolerance, col.plot, verbose=TRUE, plot=TRUE)

Arguments

y

A numeric response vector

X

A data frame of numeric variables

X.3D

A 3-D or stacked array of numeric variables, where each stack represents a particular level of covariates (i.e., individual- and area-level variables at more than one spatial scale). In cases where values are only present for a covariate at certain levels, that covariate is assigned missing values at all other levels.

ss

A vector of names to identify the different levels of covariates available as potential candidates for model input

increment

A positive step size

tolerance

A small, positive value used as a stopping criterion when none of the predictors are correlated with the residuals. The algorithm stops if the overall maximum correlation is less than a specified tolerance.

col.plot

A vector of colors (corresponding to each SS) used in the coefficient path plot

verbose

If TRUE, details are printed as the algorithm progresses

plot

If TRUE, a coefficient path plot is generated

Value

A list with the following items:

Details

This function estimates coefficients using the SS forward stagewise regression approach. The function also provides summary details and plots a coefficient path plot.

References

Grant LP, Gennings C, Wheeler, DC. (2015). Selecting spatial scale of covariates in regression models of environmental exposures. Cancer Informatics, 14(S2), 81-96. doi: 10.4137/CIN.S17302

Examples

data(y)
data(X)
data(X.3D)
ss <- c("ind", "ss1", "ss2")
mod_forward.stage.ss_0.1 <- stagewise.ss(y, X ,X.3D, ss, 0.1, 0.1, c("black", "red", "green"))