Finding the Mode of a Variable from Raw Data

Load Table 6 from Section 2.3 into R. Recall, Table 6 from Section 3.1 is Table 1 from Section 2.1

Table6 <- read.csv("https://sullystats.github.io/Statistics6e/Data/Chapter2/Table1.csv")
head(Table6,n=5)

##   Location
## 1     Back
## 2    Wrist
## 3    Elbow
## 4     Back
## 5      Hip

R does not have a built-in function for calculating the mode of a vector of numbers. Use the following workaround to calculate the mode.

x <- table(Table6)
names(x)[which(x==max(x))]

## [1] "Back"

Beware that this calculation is a workaround and does not work if there is no mode. For example, if we have a vector of 10 unique numbers (like Example 8 in the text), since each data value only occurs once, there is no mode. This workaround calculation does not understand that and will still return every data value as the mode.

Using Tally command in Mosaic

A second option for finding the mode is to build a frequency distribution of the raw data and find the most popular value. This requires the Mosaic package.

install.packages("mosaic")

library(mosaic)
tally(~Location,data=Table6)

## Location
##     Back    Elbow    Groin     Hand      Hip     Knee     Neck Shoulder 
##       12        1        1        2        2        5        1        4 
##    Wrist 
##        2

The most popular location is Back.