File:Standard deviation diagram.svg

Original file(SVG file, nominally 400 × 200 pixels, file size: 17 KB)

Summary

 Description English: Normal distribution curve that illustrates standard deviations. Each band has 1 standard deviation, and the labels indicate the approximate proportion of area (note: these add up to 99.8%, and not 100% because of rounding for presentation.) Français : Courbe de distribution normale montrant l'écart type. Chaque bande verticale a une largeur d'un écart type et les pourcentages indiquent leur valeur approximative rapportée à la population totale. Note : du fait des arrondis, le total est de 99,8 % au lieu de 100%. Date 7 April 2007 Source Own work, based (in concept) on figure by Jeremy Kemp, on 2005-02-09 Author M. W. Toews Other versions

Licensing  This file is licensed under the Creative Commons Attribution 2.5 Generic license. You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.

R code

```svg(filename = "Standard deviation diagram.svg", width = 7, height = 3.5)
par(mar = c(2, 2, 0, 0))

# # External package to generate four shades of blue
# library(RColorBrewer)
# cols <- rev(brewer.pal(4, "Blues"))
cols <- c("#2171B5", "#6BAED6", "#BDD7E7", "#EFF3FF")

# Sequence between -4 and 4 with 0.1 steps
x <- seq(-4, 4, 0.1)

# Plot an empty chart with tight axis boundaries, and axis lines on bottom and left
plot(x, type="n", xaxs="i", yaxs="i", xlim=c(-4, 4), ylim=c(0, 0.4),
bty="l", xaxt="n", xlab="", ylab="")

# Function to plot each coloured portion of the curve, between "a" and "b" as a
# polygon; the function "dnorm" is the normal probability density function
polysection <- function(a, b, col, n=11){
dx <- seq(a, b, length.out=n)
polygon(c(a, dx, b), c(0, dnorm(dx), 0), col=col, border=NA)
# draw a white vertical line on "inside" side to separate each section
segments(a, 0, a, dnorm(a), col="white")
}

# Build the four left and right portions of this bell curve
for(i in 0:3){
polysection(     i, i + 1, col=cols[i + 1])  # Right side of 0
polysection(-i - 1,    -i, col=cols[i + 1])  # Left right of 0
}

# Black outline of bell curve
lines(x, dnorm(x))

# Bottom axis values, where sigma represents standard deviation and mu is the mean
axis(1, at=-3:3, labels=expression(mu - 3 * sigma, mu - 2 * sigma, mu - sigma, mu,
mu + sigma, mu + 2 * sigma, mu + 3 * sigma))

# Add percent densities to each division (rounded to 1 decimal place), between x and x+1
text(c((0:3) + 0.5, (0:-3) - 0.5), c(0.16, 0.05, 0.04, 0.02),
sprintf("%.1f%%", 100 * (pnorm(1:4) - pnorm(0:3))),
col=c("white", "white", "black", "black"))
segments(c(-2.5, -3.5, 2.5, 3.5), dnorm(c(2.5, 3.5)),
c(-2.5, -3.5, 2.5, 3.5), c(0.03, 0.01))

dev.off()
```

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current02:06, 15 January 2015 400 × 200 (17 KB)GliderMavenAverage is now zero not mu
11:08, 7 April 2007 400 × 200 (14 KB)Petter Strandmark== Summary == Standard deviation diagram, based an original graph by Jeremy Kemp, in 2005-02-09 [http://pbeirne.com/Programming/gaussian.ps]. This figure was started in R using: <pre> x <- seq(-4,4,.1) plot(x,dnorm(x),type

Global file usage

The following other wikis use this file:

• Usage on ar.wikipedia.org
• Usage on ast.wikipedia.org
• Usage on be.wikipedia.org
• Usage on bg.wikipedia.org
• Usage on bs.wikipedia.org
• Usage on ca.wikipedia.org
• Usage on cs.wikipedia.org
• Usage on cv.wikipedia.org
• Usage on da.wikipedia.org
• Usage on de.wikipedia.org
• Usage on de.wikiversity.org
• Usage on el.wikipedia.org
• Usage on en.wikibooks.org
• Usage on es.wikipedia.org
• Usage on et.wikipedia.org
• Usage on eu.wikipedia.org
• Usage on fa.wikipedia.org
• Usage on fi.wikipedia.org
• Usage on fi.wiktionary.org
• Usage on fr.wikipedia.org
• Usage on fr.wiktionary.org
• Usage on gl.wikipedia.org

View more global usage of this file.