Monday, July 11, 2011

Stem and leaf plot




Stem and leaf plots are another data analysis method that shows the frequency with which certain classes of values occur. It is a device used for presenting quantitative data in a format which is easy to read and analyze. It is very similar to a histogram and assists in visualizing the shape of a distribution of data. The example above is showing a series of 4th grade test scores. The values on the left of the vertical bar represent the "stem" while the values on the right represent the "leaf". Instead of having to list all the grades individually, the stem and leaf plot can show them grouped together. To read this type of plot you take one stem value and pair it with one corresponding number to its right. In the last column for exampled the grades are seen as: 96, 97, 98 and 99.

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