Q-Q Diagram Confidence Intervals Panels

Panel function to go along with lattice::qqmath() and lattice::panel.qqmathline(). Adds filled confidence bands to the Q-Q-plot.

Usage

panel.qqmathci(
  x,
  y = x,
  distribution = qnorm,
  probs = c(0.25, 0.75),
  qtype = 7,
  groups = NULL,
  ci = 0.95,
  alpha = 0.25,
  col = trellis.par.get("plot.line")$col,
  ...,
  col.line
)

Arguments

x: The original sample, possibly reduced to a fewer number of quantiles, as determined by the f.value argument to qqmath
y: an alias for x for backwards compatibility
distribution: quantile function for reference theoretical distribution.
probs: numeric vector of length two, representing probabilities. Corresponding quantile pairs define the line drawn.
qtype: the type of quantile computation used in quantile
groups: optional grouping variable. If non-null, a line will be drawn for each group.
ci: Confidence level
alpha: Alpha level for the color fill
col: Color fill for the confidence bands.
...: Arguments passed to lattice::panel.superpose() and lattice::panel.polygon()
col.line: Color fill for the confidence bands. Is used internally by lattice::panel.superpose() and should generally not be changed.

Value

Augments a trellis plot panel, such as that created by lattice::qqmath(), with confidence levels.

Details

The function tries to figure out the density function counterpart to that provided in the argument distribution by regular expressions.

Author

Johan Larsson.

Examples

qqmath(~ height | voice.part, aspect = "xy", data = singer,
       prepanel = prepanel.qqmathline,
       panel = function(x, ...) {
         panel.qqmathci(x, ...)
         panel.qqmathline(x, ...)
         panel.qqmath(x, ...)
       })