SciencesPo (version 1.3.8)

draw.norm: Shades Normal Distribuion

Description

Produces a plot of a normal density distribution with shaded areas.

Usage

draw.norm(below = NULL, above = NULL, pcts = c(0.025, 0.975), mu = 0,
  sigma = 1, numpts = 500, color = "gray", dens = 40,
  justabove = FALSE, justbelow = FALSE, lines = FALSE, between = NULL,
  outside = NULL)

Arguments

below

sets a lower endpoint.

above

sets an upper endpoint.

pcts

the

mu

the mean.

sigma

standard deviations.

numpts

the number os points/observations to drawn upon.

color

the color of the area.

dens

the density of the color.

justabove

just plots the upper tail.

justbelow

just plots the lower tail.

lines

to draw lines.

between

plots between specified points.

outside

alternative "outside" area.

Value

• A plot with a normal distribution density with shaded areas

encoding

UTF-8

Examples

draw.norm()
draw.norm(below=-1.5)
draw.norm(below=-1.5,justbelow=TRUE)
draw.norm(above=1.5, justabove=TRUE)
draw.norm(below=-1.5,above=1.5)
draw.norm(between=c(-4,0),color="black")
draw.norm(between=c(0,4),color="black")
draw.norm(between=c(-1,+1),color="darkgray")
title("P[-1 < z < 1] = 68%")
draw.norm(between=c(-2,+2),color="darkgray")
title("P[-2 < z < 2] = 95%")
draw.norm(between=c(-3,+3),color="darkgray")
title("P[-3 < z < 3] = 99.7%")
draw.norm(between = c(-1.75, 0, 2, 0.5, -1))  ## Plots between specified points
draw.norm(below=50,justbelow=TRUE,color="black",mu=47.3,sigma=9.3)

## Can plot one and then another on top of it using lines = TRUE
draw.norm(mu=2, sigma=10, outside=c(-3, 12), dens=15)
draw.norm(mu=2, sigma=15, between=c(-3, 12),lines=TRUE, col="blue",dens=15)
## Example: Plotting a Hypothesis Test for the mean
## Truth:      mu.true  = 8
## Hypothesis: mu.ho    = 6
## Generate Data Under Truth
mu.true = 5 ## Alternative Mean
mu.ho   = 6
sig     = 8
N       = 250 ## Sample Size

std.err = sig/sqrt(N)
crits = qnorm(c(0.025,0.975),mean=mu.ho, sd = std.err)
draw.norm(outside = crits, mu = mu.ho, sigma = std.err,dens=15)
draw.norm(between = crits, mu = mu.true, sigma = std.err, lines=TRUE, color="green",dens=15)