2022 Introduction to Statistics in Research Mitchell 2nd ed

I N T R O T O R E S E A R C H : D A T A V I S U A L I Z A T I O N & C O M M O N S T A T T E S T S

2) There appears to be an unusual observation where one student had 2 answers correct and the next closest observation is 5.

Stem-and-leaf

The stem-and-leaf plot is a graphical display with a single column of stems with the leaves for one data set listed to the right of the stems. The stem represents a common set of place values. The leaves represent the last digit of each number.

Assume we have the following set of data to represent the number of hours worked this week:

19, 15, 40, 41, 22, 10, 37, 26, 41, 37, 12, 5, 41, 39, 16, 9

First, arrange the list of hours in order.

5, 9, 10, 12, 15, 16, 19, 22, 26, 37, 37, 39, 40, 41, 41, 41

Now to make the stem-and-leaf display shown below. Note that the stems are the tens place digits from each data value. The leaves are the ones place digits from each value. This one I did by hand. Excel does not have the functionality to create stem and leaf plots.

Table 89: Stem and Leaf, by hand

Stem and Leaf Plot – Online Calculator

Both dot plots and stem-and-leaf displays work best with a small number of data values. Stem and leaf plots are pretty easy to do by hand, but if you have a large number of points, you may want to use an online stem and leaf plot generator. One such online calculator is Calculator Soup® just by entering the values separated by commas (they don’t need to be in order , I just copied that group). Calculator Soup® provides more basic statistics including the range, count, sum, mean, median, mode, standard deviation and variance as part of the stem and leaf plot and this calculator has many other statistical capabilities!

Table 90: Stem and Leaf using Calculator Soup's Stem and Leaf Plot Calculator

One place to do this online is at

Calculator Soup® Stem-and-leaf plot found at https://www.calculatorsoup.com/calculators/statistics/stemleaf.php

Descriptive Statistics found at https://tinyurl.com/f8cac9bs

98