QQ-plots of DPIT residuals — qqresid • assessor

Makes a QQ-plot of the DPIT residuals calculated from resid_disc(), resid_semiconti() or resid_zeroinfl(). The plot should be close to the diagonal if the model is correctly specified. Note that this function does not return residuals. To get both residuals and QQ-plot, use resid_disc(), resid_semiconti() and resid_zeroinfl().

Usage

qqresid(model, scale="normal")

Arguments

model: Fitted model object (e.g., glm(), glm.nb(), zeroinfl(), and polr())
scale: You can choose the scale of the residuals between normal and uniform scales. The sample quantiles of the residuals are plotted against the theoretical quantiles of a standard normal distribution under the normal scale, and against the theoretical quantiles of a uniform (0,1) distribution under the uniform scale. The defalut scale is normal.

Value

A QQ plot.

x-axis: Theoretical quantiles
y-axis: Sample quantiles generated by DPIT residuals

See also

resid_disc(), resid_semiconti(), resid_zeroinfl()

Examples

n <- 100
b <- c(2, 1, -2)
x1 <- rnorm(n)
x2 <- rbinom(n, 1, 0.7)
y <- rpois(n, exp(b[1] + b[2] * x1 + b[3] * x2))

m1 <- glm(y ~ x1 + x2, family = poisson)
qqresid(m1, scale = "normal")

qqresid(m1, scale = "uniform")