Graphs

Qualitative Graphs

cars=c(30,50, 20)
names(cars)=c("Blue Car Sales","Red Car Sales", "Green Car Sales")
barplot(cars, main="Car Sales by Color", ylab="Frequency", col=c("blue","red", "green"))

mylab=paste(names(cars),"\n", cars, sep="")
pie(cars, main="Car Sales by Color", ylab="Frequency", labels=mylab,col=c("blue","red", "green"))

Example of Quantitative Graphs

par(mfrow=c(3,1))  #3 x 1 graphing space
myhist=hist(na.omit(airquality$Ozone), plot=FALSE) #hist  ogram

names(myhist$counts)=paste("[",myhist$breaks[1:9],", ",myhist$breaks[2:10],")", sep="") #making the names for the graph

barplot(myhist$counts, space=0, main="Histogram, Ozone Levels in NY, May-Sep 1973", xlab="Ozone, ppb", ylab="Counts", col="red")

barplot(myhist$counts/sum(myhist$counts), col="yellow",space=0, main="Rel. Freq. Histogram, Ozone Levels in NY, May-Sep 1973", xlab="Ozone, ppb", ylab="Proportion")
mycol <- rgb(0, 0, 255, max = 255, alpha = 75, names = "blue50")
polygon(c(0,seq(.5,8.5, by=1),8.5),c(0,myhist$density*20,0), col=mycol)

boxplot(na.omit(airquality$Ozone),main="Ozone example", horizontal=TRUE)

#Density Plot and CDF Plot

mydensity=density(na.omit(airquality$Ozone))
mydensity$y=mydensity$y*20
plot(mydensity,main="Example Density Plot, Ozone Data",col="red",xlab="Ozone, ppb",ylab="Proportion")

plot(ecdf(na.omit(airquality$Ozone)),main="Cumulative Distribution Function, Ozone Example", xlab="f(x)=Ozone, ppb", ylab="F(x)")

Example of the Psych Package and Manual Calculations

j=JohnsonJohnson
x1=mean(j) # mean
x2=median(j) # median
x3=max(j)-min(j) #range
x4=sum(abs(j-mean(j))/length(j)) #mean abs dev
x5=mad(j) #median abs dev
x6=var(j) #variance
x7=sd(j) #sd

results = round(c(x1, x2, x3, x4, x5, x6, x7),3)
names(results)=c("Mean", "Median", "Range", "Mn Abs Dev", "Md Abs Dev", "Var", "Sd")

results
##       Mean     Median      Range Mn Abs Dev Md Abs Dev        Var 
##      4.800      3.510     15.760      3.554      3.840     18.576 
##         Sd 
##      4.310
require(psych)
## Loading required package: psych
describe(j)
##    vars  n mean   sd median trimmed  mad  min  max range skew kurtosis
## X1    1 84  4.8 4.31   3.51     4.2 3.84 0.44 16.2 15.76 0.99    -0.05
##      se
## X1 0.47

Example of Group Mean

freq=c(6,18,11, 11, 3, 1)


mids=c(25, 35, 45, 55, 65, 75)
mymean=sum(freq*mids)/sum(freq)
mymean
## [1] 43

Measures of Location

par(mfrow=(c(3,1)))
hist(JohnsonJohnson,main="J&J Example")
boxplot(JohnsonJohnson,main="J&J Example", horizontal=TRUE)
quarter=factor(rep(seq(1:4),21))
boxplot(JohnsonJohnson~quarter, notch=T, col=seq(1:4), main="J&J by Quarter")
## Warning in bxp(list(stats = structure(c(0.61, 1.16, 2.79, 6.93, 14.04,
## 0.63, : some notches went outside hinges ('box'): maybe set notch=FALSE

Quantile

quantile(j, c(0,.25, .5, .75, 1))
##      0%     25%     50%     75%    100% 
##  0.4400  1.2475  3.5100  7.1325 16.2000
fivenum(j)
## [1]  0.440  1.245  3.510  7.335 16.200