We now have enough data to calculate the first moving range.
| Module | A6 | A5 | ||||||
|---|---|---|---|---|---|---|---|---|
| Date Completed | 20/8 | 21/8 | ||||||
| Actual | 33.0 | 37.5 | ||||||
| Estimated | 37.5 | 30.0 | ||||||
| X | -4.5 | 7.5 | ||||||
| mR |
Remember that the moving range is just like the range for a subgroup of size 2. To calculate it we need to subtract the smaller X value from the greater:
Or because the two negatives combine to make a positive, we could say:
So what is the first moving range?