# R/rsPlot.R In cddesja/moderate:

#### Defines functions rsPlot

```#' Regions of significance plot
#' Plots the regions of significance
#'
#' @param mod The fitted model
#' @param predictor The name of focal predictor variable
#' @param moderator The name of the moderator
#' @param lb The lower bound for the moderator
#' @param ub The upper bound for the moderator
#' @param xlab The label for the x-axis
#' @param ylab The label for the y-axis
#' @param plot.jn Logical. Shoud we plot the points when the interaction is significantly different than zero?
#' @export
rsPlot <- function(mod, predictor, moderator, lb, ub, xlab, ylab, plot.jn = FALSE){
z1 = lb
z2 = ub
z <- seq(z1, z2, length = 1000)
coefs <- coef(mod)
int <- coefs[match(predictor, names(coefs))]
slope <- coefs[grep(":", names(coefs))]
tstat <- qt(.975, mod\$df.residual)
var.pred <- vcov(mod)[match(predictor, colnames(vcov(mod))),match(predictor, colnames(vcov(mod)))]
cov.predint <- vcov(mod)[grep(":", colnames(vcov(mod))), match(predictor, colnames(vcov(mod)))]
var.int <- vcov(mod)[grep(":", colnames(vcov(mod))),grep(":", colnames(vcov(mod)))]
y.upper <- (int + slope * z) + (tstat * sqrt(var.pred + (2 * z * cov.predint) + ((z ^ 2) * var.int)))
y.lower <- (int + slope * z) - (tstat * sqrt(var.pred + (2 * z * cov.predint) + ((z ^ 2) * var.int)))
fy <- c(y.upper, y.lower)
y.pred <- (int + slope * z)

# Calculate JN significant areas
a <- tstat^2 * var.int - slope^2
b <- 2 * (tstat^2 * cov.predint - int * slope)
c <- tstat^2 * var.pred - int^2
jn <- c((-b - sqrt(b^2 - 4 * a * c))/(2*a),
(-b + sqrt(b^2 - 4 * a * c))/(2*a))
dat.tmp <- data.frame(z, low = y.lower,
upper = y.upper)

if(plot.jn){
plot(y.pred ~ z, type = "n", ylim = c(min(y.lower), max(y.upper)), xlab = xlab, ylab = ylab)
abline(v = jn, col = rgb(0, 0, 1, 0.5))
abline(h = 0, col = rgb(0, 0, 0, 0.5))
lines(z, y.pred)
lines(z, y.lower, lty = 2)
lines(z, y.upper, lty = 2)
} else {
plot(y.pred ~ z, type = "n", ylim = c(min(y.lower), max(y.upper)), xlab = xlab, ylab = ylab)
abline(h = 0, col = rgb(0, 0, 0, 0.5))
lines(z, y.pred)
lines(z, y.lower, lty = 2)
lines(z, y.upper, lty = 2)
}
}
```
cddesja/moderate documentation built on Jan. 29, 2019, 6:20 p.m.