Starting Up

First we need to make the package available to knitr and look at it.

library(babynames)
str(babynames)

## Classes 'tbl_df', 'tbl' and 'data.frame':    1825433 obs. of  5 variables:
##  $ year: num  1880 1880 1880 1880 1880 1880 1880 1880 1880 1880 ...
##  $ sex : chr  "F" "F" "F" "F" ...
##  $ name: chr  "Mary" "Anna" "Emma" "Elizabeth" ...
##  $ n   : int  7065 2604 2003 1939 1746 1578 1472 1414 1320 1288 ...
##  $ prop: num  0.0724 0.0267 0.0205 0.0199 0.0179 ...

summary(babynames)

##       year          sex                name                 n          
##  Min.   :1880   Length:1825433     Length:1825433     Min.   :    5.0  
##  1st Qu.:1949   Class :character   Class :character   1st Qu.:    7.0  
##  Median :1982   Mode  :character   Mode  :character   Median :   12.0  
##  Mean   :1973                                         Mean   :  184.7  
##  3rd Qu.:2001                                         3rd Qu.:   32.0  
##  Max.   :2014                                         Max.   :99680.0  
##       prop          
##  Min.   :2.260e-06  
##  1st Qu.:3.910e-06  
##  Median :7.390e-06  
##  Mean   :1.407e-04  
##  3rd Qu.:2.346e-05  
##  Max.   :8.155e-02

How Popular is Harold?

First, get the records with name = “Harold”

harolds = babynames[babynames$name=="Harold",]
str(harolds)

## Classes 'tbl_df', 'tbl' and 'data.frame':    229 obs. of  5 variables:
##  $ year: num  1880 1881 1882 1883 1884 ...
##  $ sex : chr  "M" "M" "M" "M" ...
##  $ name: chr  "Harold" "Harold" "Harold" "Harold" ...
##  $ n   : int  113 120 127 108 191 201 224 279 298 340 ...
##  $ prop: num  0.000954 0.001108 0.001041 0.00096 0.001556 ...

summary(harolds)

##       year          sex                name                 n        
##  Min.   :1880   Length:229         Length:229         Min.   :    5  
##  1st Qu.:1917   Class :character   Class :character   1st Qu.:   25  
##  Median :1946   Mode  :character   Mode  :character   Median :  350  
##  Mean   :1946                                         Mean   : 2408  
##  3rd Qu.:1974                                         3rd Qu.: 2768  
##  Max.   :2014                                         Max.   :14156  
##       prop          
##  Min.   :2.774e-06  
##  1st Qu.:2.490e-05  
##  Median :2.586e-04  
##  Mean   :2.640e-03  
##  3rd Qu.:4.336e-03  
##  Max.   :1.243e-02

Plot the number and proportion for Harold over time.

plot(harolds$year,harolds$n,main = "Count")

plot(harolds$year,harolds$prop,main = "Proportion")

Why do we get two sets of points? Some Harolds are girls!!??

table(harolds$sex)

## 
##   F   M 
##  94 135

girlHarolds = harolds[harolds$sex=="F",]
boxplot(girlHarolds$n,main = "Girls Named Harold",horizontal=TRUE)

plot(girlHarolds$year,girlHarolds$n, main = "Girls Named Harold")

How many of you know a girl named Harold (or a boy named Sue)?

You may want to read this blog post from the Census Bureau.

http://blogs.census.gov/2011/09/27/how-small-errors-can-have-a-big-impact-on-small-populations/