plot.sm {npreg}

Plot Effects for Smooth Model Fits

Description

Plots the main and two-way interaction effects for objects of class "sm".

Usage

## S3 method for class 'sm'
plot(x, terms = x$terms, se = TRUE, n = 201, intercept = FALSE,
     ask = prod(par("mfcol")) < length(terms) && dev.interactive(),
     zero.line = TRUE, zero.lty = 3, zero.col = "black", ncolor = 21, 
     colors = NULL, rev = FALSE, zlim = NULL, lty.col = NULL, 
     legend.xy = "top", main = NULL, xlab = NULL, ylab = NULL, ...)

Arguments

x

a fit from sm.

terms

which terms to include in the plot. The default plots all terms.

se

a switch indicating if standard errors are required.

n

number of points to use for line plots. Note sqrt(n) points are used for image plots.

intercept

a switch indicating if an intercept should be added to the effect plot(s).

ask

a swith indicating if the user should be prompted before switching plots (if length(terms) > 1)

zero.line

a switch indicating if the zero line should be added to the effect plot(s).

zero.lty

line type for the zero line (if zero.line = TRUE).

zero.col

color for the zero line (if zero.line = TRUE).

ncolor

number of colors to use for image plot(s).

colors

colors to use for image plots. Can input the name of a color palette (see hcl.colors) or a vector of colors to create a palette (see colorRampPalette).

rev

if colors is the name of a palette, should it be reversed? See hcl.colors.

zlim

limits to use for image plot(s) when mapping numbers to colors.

lty.col

color(s) to use for lines when plotting effects of continuous predictors.

legend.xy

location to place the legend for line plots involving interactions.

main

title for plot (ignored unless plotting a single term).

xlab

x-axis label for plot (ignored unless plotting a single term).

ylab

y-axis label for plot (ignored unless plotting a single term).

...

additional arguments passed to plotci or image

Details

Plots main and two-way interaction effects for fit smooth models using either line or image plots. The terms arugment can be used to plot a specific effect term. Main and interaction effects are plotted by creating predictions from the fit model that only include the requested terms (see predict.sm), and then using either the plotci function (for line plots) or the image function (for heatmaps).

Value

Produces a line or image plot for each requested term in the model.

Note

Three-way interaction effects are not plotted.

Author(s)

Nathaniel E. Helwig <[e-mail]>

References

Helwig, N. E. (2020). Multiple and Generalized Nonparametric Regression. In P. Atkinson, S. Delamont, A. Cernat, J. W. Sakshaug, & R. A. Williams (Eds.), SAGE Research Methods Foundations. https://doi.org/10.4135/9781526421036885885

See Also

sm for fitting sm objects.

Examples

# see examples in sm() help file
?sm