qqgig function

Generalized Inverse Gaussian Quantile-Quantile and Percent-Percent Plots

qqgig produces a generalized inverse Gaussian QQ plot of the values in y.

ppgig produces a generalized inverse Gaussian PP (percent-percent) or probability plot of the values in y.

If line = TRUE, a line with zero intercept and unit slope is added to the plot.

Graphical parameters may be given as arguments to qqgig, and ppgig.

qqgig(y, Theta, main = "GIG Q-Q Plot",
  xlab = "Theoretical Quantiles",
  ylab = "Sample Quantiles",
  plot.it = TRUE, line = TRUE, ...)

ppgig(y, Theta, main = "GIG P-P Plot",
  xlab = "Uniform Quantiles",
  ylab = "Probability-integral-transformed Data",
  plot.it = TRUE, line = TRUE, ...)

Arguments

• y: The data sample.
• Theta: Parameters of the generalized inverse Gaussian distribution.
• xlab, ylab, main: Plot labels.
• plot.it: Logical. TRUE denotes the results should be plotted.
• line: Logical. If TRUE, a line with zero intercept and unit slope is added to the plot.
• ...: Further graphical parameters.

Returns

For qqgig and ppgig, a list with components: - x: The x coordinates of the points that are be plotted.

• y: The y coordinates of the points that are be plotted.

References

Wilk, M. B. and Gnanadesikan, R. (1968) Probability plotting methods for the analysis of data. Biometrika. 55 , 1--17.

See Also

ppoints, dgig.

Examples

par(mfrow=c(1,2))
y <- rgig(1000,c(1,2,3))
qqgig(y,c(1,2,3),line=FALSE)
abline(0,1,col=2)
ppgig(y,c(1,2,3))