A MINITAB stemplot for this data (created using the
"STEM" command) is shown to the left. MINITAB first truncates the data by rounding down
to integers, then sorts the data. The resulting dataset is the following:
1, 4, 5, 8, 9, 9, 10, 10, 10, 10, 12, 12, 13, 13, 13, 14, 14, 15, 15, 15, 16, 16, 17, 18, 23.
The first column of the MINITAB stemplot counts the number of values from the top down and from the bottom up to the middle value (the median). The number in parantheses represents the count of values in the row containing the median, which is the thirteenth ordered value in this example, 13.0.
The second column plots the stems, tens of milligrams of carbon monoxide content. Because the range of the data is small (the values for the stems are 0, 1, and 2), MINITAB divides the third column, which plots milligrams as leaves, into fifths. In other words, the first row includes the leaf values 0 and 1, the second row includes the leaf values 2 and 3, etc. Since there are no values between 1.5 and 4.9, the second row contains no data points. The stemplot illustrates that the majority of the measurements lie in the teens, with only 6 of the 25 values less than 10 and only 1 value greater than 20.
Data source: Mendenhall, William, and Sincich, Terry (1992), Statistics for
Engineering and the Sciences (3rd ed.), New York: Dellen Publishing
Co. (ISBN: 0 02380552 8) (Original source: Federal Trade Commission, USA)
Dataset available through the
JSE Dataset Archive.
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