qgnorm: Graphical display for a normal distribution, given a...

In bcdudek/bcdstats: A collection of functions to support B. Dudek's APSY510/511 classes

Graphical display for a normal distribution, given a specified tail probability

Description

A function to draw a normal distribution and shade the region(s) defined by the probability argument

Usage

qgnorm(prob, mean = 0, sd = 1, tail = "upper")

Arguments

prob	The tail probability value to define the region to be shaded on the graph and the corresponding quantile to be displayed. note that if tail="two", this probability is halved for display in each tail.
mean	mean is the Distribution Mean
sd	sd is the Distribution Standard Deviation
tail	Area(s) to be shaded on the graph. If "upper", the function returns a graph with the upper tail area shaded and the upper tail probability displayed. If "lower", the function returns a graph with the lower tail area shaded and the lower tail probability displayed. If "two" the function returns a graph with both tails shaded and the specified probability is halved between these two tails. tail="upper" is the default.

Warning

Specifying extremely high or low probabilities may not yield visible shaded areas if the regions are beyond the limits of the X axis scale of the graph.

Note

This function can be very helpful in instructional situations and can replace the "t table" from textbooks.

Author(s)

Bruce Dudek [e-mail]

Examples

qgnorm(.35,mean=2000,sd=400) #shows upper tail by default
qgnorm(.16,mean=100,sd=15,tail="upper")
qgnorm(.16,mean=100,sd=15,tail="lower")
qgnorm(.975,mean=100,sd=15,tail="lower")
qgnorm(.025,mean=0,sd=1,tail="upper")
#note that pgnormz also yields the std normal
#without mean and sd arguments required#'

bcdudek/bcdstats documentation built on Jan. 3, 2024, 10:09 p.m.