qqigt {ig}R Documentation

Quantile versus quantile plot for the the IGTD

Description

The function qqigt() produces a quantile-quantile (QQ) plot for the IGTD based on the MLE of their parameters. Also, a line going through the first and the third quartile can be sketched. In addition, the coefficient of determination of least squares for the fit line is given.

Usage

qqigt(x, kernel = "normal", line = FALSE, xLabel = "Empirical quantiles", 
      yLabel = "Theoretical quantiles")

Arguments

x Vector of observations.
kernel Kernel of the pdf of the associated symmetrical distribution by means of which the IGTD is obtained. The kernels: "laplace", "logistic", "normal" and "t" are available.
line Logical; if TRUE (default), a line going by the first and third quartile is sketched.
xLabel A title for the x axis.
yLabel A title for the x axis.

Details

The function qqigt() carries out a QQ plot for the IGTD.

Value

The function qqigt() carries out an graphical plot useful as goodness-of-fit tool.

Author(s)

Víctor Leiva <victor.leiva@uv.cl; victor.leiva@yahoo.com>,
Hugo Hernández <hugo.hernandez.p@gmail.com> and
Antonio Sanhueza <asanhueza@ufro.cl>.

References

Sanhueza, A., Leiva, V., Balakrishnan, N. (2008). A new class of inverse Gaussian type distributions. Metrika (in press).

Examples

## Generates a sample from the IGTD with normal kernel
x <- rigt(300, mu = 1.0, lambda = 1.0, kernel = "normal")

## Produces a QQ plot for the IGTD with normal kernel
qqigt(x, kernel = "normal", line = TRUE)

[Package ig version 1.2 Index]