Individual Measurements and I-MR Charts
An Individuals chart tracks each ordered value. The Moving Range chart tracks the absolute difference between successive values and supplies the short-term variation estimate used for the Individuals limits.
Technical publication review required before indexing · Draft reviewed 13 August 2026
Engineering workflow
- Keep values in collection order.
- Use consecutive pairs for a two-point moving range.
- Investigate both beyond-limit points and non-random patterns.
- Freeze baseline limits only after a defensible stable period.
Worked example
If the average moving range is 0.012 mm, estimated sigma is 0.012/1.128 = 0.01064 mm. Individuals limits are the mean ±2.66×0.012.
Build an I-MR chartLimitations and checks
- Autocorrelation can distort limits.
- I-MR is not a workaround for avoidable subgrouping problems.
Relevant AccuTouch next step
Use the calculation as a screening input, then confirm the actual gauge, fixture, software or automation configuration.
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