Creating a Freq. Dist. Using Grouped Quantitative
Data (Histogram)
o Number of classes should ideally be between 4 and 20
▪ One method to determine the number of classes is
• 2k n, where k = number of classes, n = number
of data points
▪ once k is known, the width is found by:
• Estimated class width = (Max data value –
minimum data value)/k
o Round to whole number
• Class boundaries – the minimum and maximum values for each
class
o choose class boundaries that are easy to read
*Rules for Classes for Grouped Data*
1. Equal-size classes.
2. Mutually exclusive classes: class boundaries cannot
overlap.
3. Include all data values.
4. Avoid empty classes.
5. Avoid open-ended classes: infinite.
• Some data are technically discrete but displayed in a
continuous format
find more resources at oneclass.com
find more resources at oneclass.com