Usually, you create an R chart from a column of individual measurements. However, you can also create an R chart from a column of subgroup ranges.

To create an R chart, Minitab needs to know the range and the sample size for each subgroup. For example, suppose that each row contains individual measurements for a subgroup. If a row contains the measurements 2, 6, and 7, Minitab calculates the range for the subgroup as 5 (7 minus 2) and the subgroup size as 3.

Now suppose that you only have a column of subgroup ranges, but you know that the subgroup size is 3. You can create 2 columns of zeros so that Minitab will calculate the correct ranges and sample sizes. For example, a row that contains the values 5, 0, and 0 results in the same range and subgroup size as a row that contains the individual measurements of 2, 6, and 7.

## Example of creating an R chart using subgroup range data

For example, suppose that column C1 contains the ranges for 20 subgroups, and the subgroup size is 3.

- Enter 20 zeros in C2 and 20 zeros in C3. To enter all the zeros for a column in a single step, use .
- Choose .
- Choose Observations for a subgroup are in one row of columns from the drop-down list, then enter
`C1 C2 C3`.
- Click OK.