Stem and Leaf Plot

Data representation technique. Easier to work on large sets of data.Let us consider the following data set – new, which has 80 points. Representing this data can be a task.new [1] 79 54 74 62 85 55 88 85 51 85 54 84 78 47 83 52 62 84 52 79 51 47 78 69 74 83 55 76 78 79 73 77 66 80 74 52 48 80 59 90 80 58 84[44] 58 73 83 64 53 82 59 75 90 54 80 54 83 71 64 77 81 59 84 48 82 60 92 78 78 65 73 82 56 79 71 62 76 60 78 76 83 54

To represent data in a relatively easier manner, we have used the stem() command following in Rstem(new)The decimal point is 1 digit(s) to the right of the |

4 | 7788 5 | 11222344444 5 | 55688999 6 | 0022244 6 | 569 7 | 11333444 7 | 5666778888889999 8 | 00001222333334444 8 | 5558 9 | 002

The numbers to the left of the line are the stem, the ones to the right are the leaves. The leaves contain the ones digit and the stem has the tens digit in this case. We can define it differently for different data sets. In this case to represent the first number in the data set – 79, we go to the “stem 7” and write “9” on the leaf side. For representing 47, we go over to “stem 4” and write “7” on the leaf side.

It also becomes relatively easier to count multiple instances (appearances) of the same number. For example, 47 appears twice in the data set, 83 appears 5 times, and 78 appears 6 times.

We will solve a few of questions now –

1. A statistician for a basketball team tracked the number of points that each of the 12 players on the team had in one game. The stem-and-leaf plot of the game is as follows. How many players scored less than 10 points? How many points did the team score?Stem | Leaf0 | 0 0 2 4 7 7 91 | 1 1 3 82 | 0

Ans. – Number of entries in stem 0 = 7Total of stem and leaves = 0+0+2+4+7+7+9+11+11+13+18+20

= 102

2. A government created the following stem-and-leaf plot showing the number of turtles at each major zoo in their country. How many zoos have less than 27 turtles? How many have greater than 33 turtles?Stem | Leaves0 | 41 | 1 4 6 6 7 82 | 3 3 6 93 | 1 2 4 5 7 8

Ans. – Less than 27 turtles – 10 zoosGreater than 33 turtles – 4 zoos