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NIST e-Handbook 6.3.2.2: I–MR chart of ten batch flow rates
| Tool | SPC and Capability |
| Source | NIST/SEMATECH (2012). "Individuals Control Charts." NIST/SEMATECH e-Handbook of Statistical Methods. Section 6.3.2.2. |
| Level | Undergraduate |
Problem
A flow-rate measurement is available only once per batch, so subgroups cannot be formed. Build an individuals chart with a moving range of 2 from the ten batch values 49.6, 47.6, 49.9, 51.3, 47.8, 51.2, 52.6, 52.4, 53.6 and 52.1 and give the limits of the individuals chart.
Inputs to Enter
- Chart type I–MR (individual values, moving range of 2)
- Data: 49.6 47.6 49.9 51.3 47.8 51.2 52.6 52.4 53.6 52.1 (one value per line or all on one line)
Answers
- x̄ = 50.81, mean moving range MR̄ = 1.8778
- Individuals chart: UCL 55.8041, LCL 45.8159 (x̄ ± 3 MR̄/1.128)
- Moving-range chart: UCL = 3.267 MR̄ = 6.134, first moving range |47.6 − 49.6| = 2.0
Notes
Choose the I–MR chart in the Chart Type select and paste the ten values in place of the default subgroups; leave the specification limits blank. The handbook page prints the same limits from the same d2 = 1.128.