President Ages

As you know, yesterday was a big day in the history of the US as Barack Obama became our 44th president.  In honor of that event, I collected the ages at inauguration and lifespans of all 44 presidents and read this dataset into R.

data=read.table("president.ages.txt",header=T,sep="\t")

I attach the dataframe to make the variables visible.

attach(data)

Then using the stem.leaf function in the aplstats package, I construct a stemplot of the president ages:

> stem.leaf(Age)

1 | 2: represents 12

 leaf unit: 1

            n: 44

   2     t | 23

         f | 

   6     s | 6677

   9    4. | 899

  15    5* | 011111

  17     t | 22

  (9)    f | 444445555

  18     s | 6667777

  11    5. | 8

  10    6* | 0111

   6     t | 2

   5     f | 445

         s | 

   2    6. | 89

What do I see?  Here are some things I notice:

• The ages at inauguration seem pretty symmetric shaped about the values of 54 or 55.
• President ages range from 42 to 69.  Actually, one has to be a particular age to be president, so I believe that 42 is close to the rule.
• Barrack Obama is one of the youngest presidents in history at 48

I didn't play with the options for stemplot -- I just used the default settings in the stem.leaf function.  Could I produce a better stemplot?

Let's break between the tens and ones with five leaves per stem.

> stem.leaf(Age,unit=1,m=2)

1 | 2: represents 12

 leaf unit: 1

            n: 44

    2    4* | 23

    9    4. | 6677899

   22    5* | 0111112244444

  (12)   5. | 555566677778

   10    6* | 0111244

    3    6. | 589

> 

Or I could go the other way and split between the ones and tenths with 10 leaves per stem.

> stem.leaf(Age,unit=.1,m=1)

1 | 2: represents 1.2

 leaf unit: 0.1

            n: 44

   1    42 | 0

   2    43 | 0

        44 | 

        45 | 

   4    46 | 00

   6    47 | 00

   7    48 | 0

   9    49 | 00

  10    50 | 0

  15    51 | 00000

  17    52 | 00

        53 | 

  22    54 | 00000

  (4)   55 | 0000

  18    56 | 000

  15    57 | 0000

  11    58 | 0

        59 | 

  10    60 | 0

   9    61 | 000

   6    62 | 0

        63 | 

   5    64 | 00

   3    65 | 0

HI: 68 69

> 

I think it is pretty obvious that the first stemplot is the best.   If I have too few lines, then I lose some of the structure of the distribution; with too many lines, I don't see any structure at all.