psre (version 0.1.2)

qqPoints: Quantile Comparison Data

Description

Makes data that can be used in quantile comparison plots.

Usage

qqPoints(
  x,
  distribution = "norm",
  line = c("quartiles", "robust", "none"),
  conf = 0.95,
  ...
)

Value

A data frame with variables x observed quantiles, theo the theoretical quantiles and lwr and upr

the confidence bounds. The slope and intercept of the line running through the points are returned as a and b as an attribute of the data.a

Arguments

x

vector of values whose quantiles will be calculated.

distribution

String giving the theoretical distribution against which the quantiles of the observed data will be compared. These need to be functions that have q and d functions in R. Defaults to "norm".

line

String giving the nature of the line that should be drawn through the points. If "quartiles", the line is drawn connecting the 25th and 75th percentiles. If "robust" a robust linear model is used to fit the line.

conf

Confidence level to be used.

...

Other parameters to be passed down to the quantile function.

Examples

x <- rchisq(100, 3)
qqdf <- qqPoints(x)
a <- attr(qqdf, "ab")[1]
b <- attr(qqdf, "ab")[2]
l <- min(qqdf$theo) * b + a
u <- max(qqdf$theo) * b + a
library(ggplot2)
ggplot(qqdf, aes(x=theo, y=x)) +
  geom_ribbon(aes(ymin=lwr, ymax=upr), alpha=.15) +
  geom_segment(aes(x=min(qqdf$theo), xend=max(qqdf$theo), y = l, yend=u)) +
  geom_point(shape=1) +
  theme_classic() +
  labs(x="Theoretical Quantiles",
       y="Observed Quantiles")