SparkNotes: Graphing Data: Histograms

SparkNotes: Graphing Data: Histograms

Frequency Distribution Tables A frequency distribution table is a table that shows how often a data point or a group of data points appears in a given data set. To make a frequency distribution table, first divide the numbers over which the data ranges into intervals of equal length. Then count how many data points fall into each interval. If there are many values, it is sometimes useful to go through all the data points in order and make a tally mark in the interval that each point falls. Then all the tally marks can be counted to see how many data points fall into each interval. The "tally system" ensures that no points will be missed. Example: The following is a list of prices (in dollars) of birthday cards found in various drug stores: 1.45 2.20 0.75 1.23 1.25 1.25 3.09 1.99 2.00 0.78 1.32 2.25 3.15 3.85 0.52 0.99 1.38 1.75 1.22 1.75 Make a frequency distribution table for this data. We omit the units (dollars) while calculating. The values go from 0.52 to 3.85 ,

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