It comes from the fact that there is 1 leaf in the first (6) stem, 0 leaves in the second (the first 7) stem, and 2 leaves in the third (the second 7) stem, and so 1 + 0 + 2 = 3. The third number in the depths column is a 3. It comes from the fact that there is 1 leaf in the first (6) stem and 0 leaves in the second (the first 7) stem, and so 1 + 0 = 1. The second number in the depths column is also a 1. It comes from the fact that there is just one number in the first (6) stem. For example, the first number in the depths column is a 1. The depths are the frequencies accumulated from the top of the plot and the bottom of the plot until they converge in the middle. That column contains what are called depths. Now, back to that first column of numbers appearing in Minitab's plot. Minitab orders the data before producing the plot, and thereby creating what is called an ordered stem-and-leaf plot. Sometimes the one row per stem option produces the better plot, and sometimes the two rows per stem plot option produces the better plot.ĭo you notice any other differences between Minitab's plot and our plot? Note that the leaves in Minitab's plot are ordered. The decision to use one or two rows for the stems depends on the data. For example, note that the first 9 row contains the 0 to 4 leaves, while the second 9 row contains the 5 to 9 leaves. When you opt to use two rows for each stem, the first row is reserved for the leaves 0, 1, 2, 3, and 4, while the second row is reserved for the leaves 5, 6, 7, 8, and 9. Minitab takes an alternative here that we could have taken as well. Note, though, that Minitab uses two rows for each of the stems 7, 8, 9, 10, 11, 12, and 13. Then, ignoring the first column of numbers for now, the second column contains the stems from 6 to 14. how does the plot differ from ours? First, Minitab tells us that there are n = 64 numbers and that the leaf unit is 1.0. Here's what Minitab's stem-and-leaf plot of the 64 IQs looks like: Stem-and-Leaf of IQ Instead, you'd probably want to let some statistical software, such as Minitab or SAS, do the work for you. First and foremost, no one in their right mind is going to want to create too many of these stem-and-leaf plots by hand. That's all well and good, but we could do better.
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