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gap (version 1.6)

qqunif: Q-Q plot for uniformly distributed random variable

Description

Q-Q plot for uniformly distributed random variable

Usage

qqunif(
  u,
  type = "unif",
  logscale = TRUE,
  base = 10,
  col = palette()[4],
  lcol = palette()[2],
  ci = FALSE,
  alpha = 0.05,
  ...
)

Value

The returned value is a list with components of a qqplot:

  • x expected value for uniform order statistics or its -log(,base) counterpart.

  • y observed value or its -log(,base) counterpart.

Arguments

u

a vector of uniformly distributed random variables.

type

string option to specify distribution: "unif"=uniform, "exp"=exponential.

logscale

to use logscale.

base

the base of the log function.

col

color for points.

lcol

color for the diagonal line.

ci

logical option to show confidence interval.

alpha

1-confidence level, e.g., 0.05.

...

other options as appropriae for the qqplot function.

Author

Jing Hua Zhao

Details

This function produces Q-Q plot for a random variable following uniform distribution with or without using log-scale. Note that the log-scale is by default for type "exp", which is a plot based on exponential order statistics. This appears to be more appropriate than the commonly used procedure whereby the expected value of uniform order statistics is directly log-transformed.

References

balakrishnan03gap

casella02gap

davison03gap

See Also

qqfun