In a frequency distribution, class width refers to the difference between the upper and lower boundaries of any class or category.
For example, the following frequency distribution has a class width of 4:
- The class width for the first class is 5 – 1 = 4
- The class width for the second class is 10 – 6 = 4
- The class width for the third class is 15 – 11 = 4
And so on.
You can calculate the class width for any dataset by using the following formula:
Class width = (max – min) / n
- max: The maximum value in the dataset
- min: The minimum value in the dataset
- n: The number of classes you want to use
The following example illustrates how to calculate class width for a dataset in Google Sheets.
Example: How to Calculate Class Width in Google Sheets
Suppose we have the following dataset of 20 values in Google Sheets:
Suppose we’d like to create a frequency distribution for this dataset using n = 5 classes.
We can use the following formula in Google Sheets to find the class width for this frequency distribution:
The following screenshot shows how to use this formula:
The class width turns out to be 4.6.
As a rule of thumb, we always round up to the nearest integer so in this case we would use a class width of 5.
Lastly, we can create a frequency table that uses a class width of 5:
Notice the following about our frequency distribution:
- The width for each class is 5.
- The sum of the values in the “Frequency” column adds up to 20. This matches the total number of values in our dataset.
We can use this general approach to calculate the class width of a frequency distribution for any dataset in Google Sheets.