ppPlot: ppPlot: Probability Plots for various distributions

In r6qualitytools: R6-Based Statistical Methods for Quality Science

ppPlot: Probability Plots for various distributions

Description

Function ppPlot creates a Probability plot of the values in x including a line.

Usage

ppPlot(
  x,
  distribution,
  confbounds = TRUE,
  alpha,
  probs,
  main,
  xlab,
  ylab,
  xlim,
  ylim,
  border = "red",
  bounds.col = "black",
  bounds.lty = 1,
  start,
  showPlot = TRUE,
  axis.y.right = FALSE,
  bw.theme = FALSE
)

Arguments

x	Numeric vector containing the sample data for the ppPlot.
distribution	Character string specifying the distribution of x. The function ppPlot will support the following character strings for distribution: `beta` `cauchy` `chi-squared` `exponential` `f` `gamma` `geometric` `log-normal` `lognormal` `logistic` `negative binomial` `normal` `Poisson` `weibull` By default distribution is set to `normal`.
confbounds	Logical value: whether to display confidence bounds. Default is TRUE.
alpha	Numeric value: significance level for confidence bounds, default is '0.05'.
probs	Vector containing the percentages for the y axis. All the values need to be between '0' and '1'. If 'probs' is missing it will be calculated internally.
main	Character string: title of the plot.
xlab	Character string: label for the x-axis.
ylab	Character string: label for the y-axis.
xlim	Numeric vector of length 2: limits for the x-axis.
ylim	Numeric vector of length 2: limits for the y-axis.
border	Character or numeric: color for the border of the line through the quantiles. Default is `red`.
bounds.col	Character or numeric: color for the confidence bounds lines. Default is `black`.
bounds.lty	Numeric or character: line type for the confidence bounds lines. This can be specified with either an integer (0-6) or a name: 0: blank 1: solid 2: dashed 3: dotted 4: dotdash 5: longdash 6: twodash Default is '1' (solid line).
start	A named list giving the parameters to be fitted with initial values. Must be supplied for some distributions (see Details).
showPlot	Logical value indicating whether to display the plot. By default, showPlot is set to TRUE.
axis.y.right	Logical value indicating whether to display the y-axis on the right side. By default, axis.y.right is set to FALSE.
bw.theme	Logical value indicating whether to use a black-and-white theme from the ggplot2 package for the plot. By default, bw.theme is set to FALSE.

Details

Distribution fitting is performed using the FitDistr function from this package. For the computation of the confidence bounds, the variance of the quantiles is estimated using the delta method, which involves the estimation of the observed Fisher Information matrix as well as the gradient of the CDF of the fitted distribution. Where possible, those values are replaced by their normal approximation.

Value

The function ppPlot returns an invisible list containing:

x	x coordinates.
y	y coordinates.
int	Intercept.
slope	Slope.
plot	The generated PP plot.

See Also

qqPlot, FitDistr.

Examples

set.seed(123)
ppPlot(rnorm(20, mean=90, sd=5), "normal",alpha=0.30)
ppPlot(rcauchy(100), "cauchy")
ppPlot(rweibull(50, shape = 1, scale = 1), "weibull")
ppPlot(rlogis(50), "logistic")
ppPlot(rlnorm(50) , "log-normal")
ppPlot(rbeta(10, 0.7, 1.5),"beta")
ppPlot(rpois(20,3), "poisson")
ppPlot(rchisq(20, 10),"chi-squared")
ppPlot(rgeom(20, prob = 1/4), "geometric")
ppPlot(rnbinom(n = 20, size = 3, prob = 0.2), "negative binomial")
ppPlot(rf(20, df1 = 10, df2 = 20), "f")

r6qualitytools documentation built on Oct. 4, 2024, 1:09 a.m.