File:Standard deviation diagram.svg

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Standard_deviation_diagram.svg‎ (SVG file, nominally 400 × 200 pixels, file size: 14 KB)

[edit] Summary

Description
English: Normal distribution curve that illustrates standard deviations
Date

7 April 2007(2007-04-07)
Source

Own work, based (in concept) on figure by Jeremy Kemp, on 2005-02-09
Author

Mwtoews
Permission
(Reusing this file)		 See below.
Other versions

  • with decimal comma

[edit] Figure source code

This figure was made in R using:

# # 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="x-value", ylab="probability density")

# 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(-3*sigma, -2*sigma, -1*sigma, mu,
                                    1*sigma,  2*sigma,  3*sigma))

# Add percent densities to each division, between x and x+1
pd <- sprintf("%.1f%%", 100*(pnorm(1:4) - pnorm(0:3)))
text(c((0:3)+0.5,(0:-3)-0.5), c(0.16, 0.05, 0.04, 0.02), pd, 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))
Rlogo.png
 This chart was created with R.

[edit] Licensing

w:en:Creative Commons
attribution		 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 attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).

File history

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

Date/TimeThumbnailDimensionsUserComment
current11:08, 7 April 2007Thumbnail for version as of 11:08, 7 April 2007400 × 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)
The following pages on the English Wikipedia link to this file (pages on other projects are not listed):

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Metadata

This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. If the file has been modified from its original state, some details may not fully reflect the modified file.
Width 400
Height 200
Retrieved from "http://en.wikipedia.org/wiki/File:Standard_deviation_diagram.svg"
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