SContinuous1DII-1-31

# SContinuous1DII-1-31 - Rebecca Nugent Department of...

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Monday January 31, 2011 Last time: Continuous 1-D (Dot Charts, Jitter, Strip Charts) Today: Continuous 1-D, Part II Next Time: More Continuous 1-D Announcements: HW 3 due 2/2 12:30pm Digital Dropbox, copy in class New study abroad scholarship fund http://www.cmu.edu/uro/jennings.index.html Review Summary x<-c(runif(50,-1,1),runif(50,1.1,1.15),runif(100,1.3,3.3)) Rebecca Nugent, Department of Statistics, Carnegie Mellon University, 2011 1

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Boxplot: a compact picture of the shape of the distribution: boxplot( ) ; see boxplot(x) \$ stats for a list of the diFerent values Can describe features of distribution from boxplot: symmetry , skew , etc. Assuming a representative sample from each distribution, Uniform: Exponential: Normal: t-distr: par(mfrow=c(2,2)) x<-runif(50,0,3); boxplot(x,col=5,main="Uniform Data on [0,3]") x<-rexp(50,2); boxplot(x,col=8,main="Exponential Data: Rate = 2") x<-rnorm(50,1.5,0.5);boxplot(x,col=6,main="Normal Data: Mean 1.5, SD 0.5") x<-rt(50,8); boxplot(x,col=7,main="T Data; df = 8")
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Unformatted text preview: Rebecca Nugent, Department of Statistics, Carnegie Mellon University, 2011 2 Comparing Distributions: boxplots need to be on same y-axis; can put two graphs next to each other with the same y-range OR can put two boxplots in the same graphics window What do we look for? par(mfrow=c(2,1)) boxplot(fat[shelf==1],fat[shelf==2],fat[shelf==3],names=c("Shelf 1","Shelf 2", "Shelf 3"),ylab="Fat in Grams per Portion") title("Fat Content by Shelf Location") boxplot(fat~mfr,ylab="Fat in Grams per Portion") title("Fat Content by Manufacturer") Boxplot Advantages? Disadvantages? Box-Percentile Plot: combining quartiles with features of a cumulative distribution function library(Hmisc); par(mfrow=c(1,2)) x<-c(runif(50,-1,1),runif(50,1.1,1.15),runif(100,1.3,3.3)) boxplot(x,col=2,main="Trimodal: Boxplot") bpplot(x,main="Trimodal: Box-Percentile Plot") Rebecca Nugent, Department of Statistics, Carnegie Mellon University, 2011 3...
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SContinuous1DII-1-31 - Rebecca Nugent Department of...

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