Index

Stem and Leaf Plot

The stem-and-leaf plot is a graphical method that describes the general shape or distribution of the data. The value of every piece of data used to construct the plot can be read off the plot, although in an approximate manner.

A stem-and-leaf plot is a special kind of histogram, which shows not only the frequency tally in each ‘bin’ as in a histogram; it also shows each individual value in the bin, thus avoiding loss of information. You may choose to specify and plot two separate data ranges, the Right and the Left ranges. 

Please note that the Stem-and-Leaf plot is not an Excel chart object; it is just a tabular output formatted in a special way. Here is what a typical stem-and-leaf plot looks like: 

Each data value is plotted in the form of a combination of a “stem” and a “leaf”. The “stem” is akin to a bin in a histogram. In this case, it represents the more significant portion of the data point, and the “leaf” gives the less significant portion. Each leaf represents one data point, whose value is equal to stem + (leaf/10), scaled to a convenient factor – a power of 10. The key at the bottom explains the magnitude or scale of the stem. If a particular data value appears more than once, it is repeated accordingly in the plot.

To learn about StatCharts Stem And Leaf Plot click on...

About the Stem and Leaf Plot Dialogbox

To create Stem and Leaf Plot, from the menu, choose Tools/StatCalc/Charts/Stem and Leaf Plot. The following dialog pops up.

Data Range is where you should specify the range containing data to be plotted. The range may consist of multiple regions. All cells in the marked regions are considered, without regard to their row or column configuration.

Title Row Exists When checked it selects the headers from first row of the selected data range else it follows the default naming convention. In this case, the variable in the first column of the selected range will be called "Var1", the second column as "Var2"..etc

Left Leaf Choose the row from the Variables  list which contains the values for the Left Leaf.

Right Leaf Choose the row from the Variables  list which contain the values for the Right Leaf. 

No. of Stem Splits  here, you can choose any one of 1, 2 and 5. A leaf always represents a single significant digit of data (0 through 9), so a total of 10 distinct leaf values are possible for each stem. When the stem split is 1, all ten leaf values are plotted on a single stem. If you choose 2, the stem is split into two, so that leaf values 0 through 4 are plotted on one stem, and the values 5 through 9 on another. Thus, there can be up to 2 occurrences of a given stem value. If you choose 5, there can be up to 5 occurrences,  to cover leaf values of 0-1, 2-3, 4-5, 6-7 and 8-9.

Stem Step Size  lets you specify the magnitude or the scale of the stem. If the step size is 0, a stem of 3 would mean actual data value of 3 (3*10^0). If the step size is 2, the stem value 3 would indicate a data value of 300 (3 * 10^2) and if it is –1, stem value 3 would mean 0.3 (3 * 10^-1).  

Chart Title allows you to provide a desired title to the chart.

X-Axis Title allows you to provide a desired title to the X Axis.

Y-Axis Title allows you to provide a desired title to the Y Axis.

Target Range here, specify the starting cell on the worksheet where you want the stem-and-leaf diagram to appear.  

Example:

The underlying data consists observations on two variables. This data set is used to draw a Stem And Leaf plot.

X1 X2
84.77774 21.92106
6.116614 1.41876
17.97268 38.35293
32.36757 70.81903
88.64472 28.44721
66.48075 2.725794
52.16064 36.73728
44.30822 79.57928
51.70094 18.8458
37.61839 81.28946
10.94024 56.51774
56.77002 9.400567
37.04025 27.67444
16.9951 57.42291
35.61144 79.13202
96.69932 36.30708
84.77739 68.55396
11.48536 29.13211
20.41793 65.13218
37.20681 37.81747

Using the data set given below and making the entries as specified in the dialog we get a Stem And Leaf Plot. From the Graph below we can get the repetitions of the numbers in the data set. From the third row of the output we can see that the number 28 has been repeated twice in the left leaf and from the fourth row the number 37 is repeated twice in the right leaf.