adespatial (version 0.0-7)

forward.sel: Forward selection with multivariate Y using permutation under reducel model

Description

Performs a forward selection by permutation of residuals under reduced model. Y can be multivariate.

Usage

forward.sel(Y, X, K = nrow(X) - 1, R2thresh = 0.99, adjR2thresh = 0.99, nperm = 999, R2more = 0.001, alpha = 0.05, Xscale = TRUE, Ycenter = TRUE, Yscale = FALSE)

Arguments

Y

Response data matrix with n rows and m columns containing quantitative variables

X

Explanatory data matrix with n rows and p columns containing quantitative variables

K

Maximum number of variables to be selected. The default is one minus the number of rows

R2thresh

Stop the forward selection procedure if the R-square of the model exceeds the stated value. This parameter can vary from 0.001 to 1

adjR2thresh

Stop the forward selection procedure if the adjusted R-square of the model exceeds the stated value. This parameter can take any value (positive or negative) smaller than 1

nperm

The number of permutation to be used.The default setting is 999 permutation.

R2more

Stop the forward selection procedure if the difference in model R-square with the previous step is lower than R2more. The default setting is 0.001

alpha

Significance level. Stop the forward selection procedure if the p-value of a variable is higher than alpha. The default is 0.05 is TRUE

Xscale

Standardize the variables in table X to variance 1. The default setting is TRUE

Ycenter

Center the variables in table Y. The default setting is TRUE

Yscale

Standardize the variables in table Y to variance 1. The default setting is FALSE.

Value

A dataframe with: A dataframe with:

Details

The forward selection will stop when either K, R2tresh, adjR2tresh, alpha and R2more has its parameter reached.

References

Canoco manual p.49

Examples

x <- matrix(rnorm(30),10,3)
y <- matrix(rnorm(50),10,5)
    
forward.sel(y,x,nperm=99, alpha = 0.5)