Dot plots are usually more useful for smaller data sets, and for larger data sets a box plot or histogram is used. DisadvantagesĪ disadvantage of stem and leaf plots is they are really only useful for small data sets from about 15 to 150 data points. They are also useful for highlighting the mode (the most common number in a data set) and for finding outliers. These types of charts give you a quick overview of a distribution and you can also see the shape of the distribution (think of each leaf as representing a bar on a bar chart). Bar graphs also show this information, but the advantage the stem and leaf plot have is that you can see all of the scores (other charts usually show just totals). In the above graph, most scores were in the 20s or 60s. Stem and leaf plots are useful in some cases because you can see where the bulk of scores lie. Stem values are listed down (ascending order, from smallest to largest) and the leaf values are listed right to left (ascending order, from smallest to largest). For example, a key next to the following stemplot tells you that 7|5 means 75, indicating that the stem represents tens and the leaf represents units. However, in textbooks and other education materials it’s common for stemplots to be labeled. Stemplots in the real world aren’t usually labeled with the place-values that the stem represents - it’s usually up to you to figure it out based on the context and the data. The largest place-value digits are placed in the stem. The stems with the largest amount of data in the picture above are the 2 and 6 stems. A very long leaf means that “stem” has a large amount of data. While a histogram uses bars to represent amounts, the leaves of the stemplot represent amounts. The stem and leaf plot is used like a histogram it allows you to compare data. They are used less frequently today, but you’ll still see some here and there. They were widely used before the advent of the personal computer, as they were a fast way to sketch data distributions by hand. The first few values from this stemplot are:Ī stem and leaf plot is a way to plot data where the data is split into stems (the largest digit) and leaves (the smallest digits). The name “Stem plot” comes because there is one “stem” with the largest place-value digits to the left (shaded in gray in the image below) and one “leaf” to the right. They are typically used when there is a medium amount of quantitative variables to analyze Stemplots of more than 50 observations are unusual. Stemplots show a little more information than a histogram and have been a common tool for displaying data sets since the 1970s. Descriptive Statistics > Stemplot / Stem and Leaf Plot What is a Stemplot?Ī stemplot is like a histogram - they are both tools to help you visualize a data set.
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