A stem and leaf plot is a graph that represents the distribution of a set of data, with information for each individual value. It is rather similar to a histogram, but it is more informative. In a stem and leaf plot, the distribution of data is based on place value, with the digits in the highest place listed under “stem” and those in the lowest place under “leaf”. The stem column is usually located to the left of the leaf column.
The stem and leaf plot is useful for organizing a large amount of data. It is the preferred method for presenting a series of rainfall measurements and temperatures over a certain period of time, series of scores or statistics of sports teams and players, as well as the test scores of students in a class. A stem and leaf plot can also be used to show two sets of data, and this makes it easier for people to compare information.
To give a better idea of how a stem and leaf plot works, it is necessary to provide explanation through an example. In the case that a stem and leaf plot is used to organize and present the test scores of students, the place values of the score of each individual student will be separated and placed under stem or leaf. The “tens” will be listed in the stem column, and the “ones” will be placed in the leaf column. Say, there are 10 students altogether, and their scores are 94, 92, 87, 85, 82, 79, 74, 66, 63, and 54. In this case, the stem column will contain five rows of numbers, which are 9, 8, 7, 6, and 5. In the leaf column, the first row will show the numbers 2 and 4, and the next row will have 2, 5, and 7. The numbers 4 and 9 will be shown in the third row, and 3 and 6 in the fourth row. The last row will have only one number, which is 4. By counting the numbers that are listed under the leaf column, one can find out the total number of students who are represented in the plot.
It is rather easy to construct a stem and leaf plot. Firstly, divide the plot into two columns, and label the left column “stem” and the right column “leaf”. Group the numbers in the data set according to their values in the highest place and list each value under the stem column, from the largest to the smallest or vice versa. For every value in the stem, a list of digits in the lowest place should be displayed on the same row, under the leaf column. Make sure that the total number of digits in the leaf column is the same as the count of numbers in the data set.
Many people think that stem and leaf plots are similar to histograms, but these two types of graphs are different in certain ways. In a stem and leaf plot, data distribution is shown with the listing of numbers, whereas a histogram represents the distribution in a graphical way. A stem and leaf plot gives a clearer presentation of a data set, but it is not the ideal method to present data that contains numbers with decimal points. A histogram is often used to show distribution of decimal numbers.
Here are a number of websites that provide information and activities for those who are interested in learning about stem and leaf plots.