Relative frequency histograms are constructed in much the same way as a frequency histogram except that the vertical axis represents the relative frequency instead of the frequency. Note that different choices of class intervals will result in different histograms. According to the include left and exclude right endpoint convention, the observation 133 is included in the class 133-135. If we do not specify the midpoint for the definition of intervals, Minitab will default to choose another set of class intervals resulting in the following histogram. The following histogram is produced by Minitab when we specify the midpoints for the definition of intervals according to the intervals chosen above. Having the intervals, one can construct the frequency table and then draw the frequency histogram or get the relative frequency histogram to construct the relative frequency histogram. For example, Minitab includes the left end point and excludes the right end point. An alternative is to specify the endpoint convention.

5 is to avoid confusion whether the end point belongs to the interval to its left or the interval to its right. The reason that we choose the end points as. Since the data range is from 132 to 148, it is convenient to have a class of width 2 since that will give us 9 intervals. Excel Data Analysis Tool: To use Excels Histogram data analysis tool, you must first establish a bin array (as for the FREQUENCY function described in. The table below shows her recorded weights in pounds.įor histograms, we usually want to have from 5 to 20 intervals. Jessica weighs herself every Saturday for the past 30 weeks.

Frequency Table To Histogram Generator