The Individual & Moving Range (I-MR) chart monitors processes where measurements are taken individually rather than in subgroups. It consists of two charts: the Individual (I) chart tracks individual measurements, while the Moving Range (MR) chart monitors the variation between consecutive measurements.
I-MR Chart Overview & Applications
Control Limits & Moving Range Formula
Reading the I-MR Chart
Example Chart & Signal Interpretation
In Control Signals
- • Individual values fluctuate randomly within limits
- • Moving ranges stay below MR chart UCL
- • No runs, trends, or alternating patterns
- • Process mean and variation appear stable
Out of Control Signals
- • Points beyond I-chart or MR-chart limits
- • A large moving range signals a sudden shift
- • 8+ consecutive points on one side of center line
- • Sustained trend indicating drift in process level
In the example above, sample 6 shows a moving range spike (1.1) flagged as a warning, and sample 7's moving range (1.3) exceeds the MR-chart UCL, signaling increased short-term variability even though the individual value remains within I-chart limits.
Implementation on sixsigmacenter.com
This platform provides comprehensive I-MR chart analysis with automated calculations and professional reporting capabilities for individual measurement monitoring.
Platform Features
- • Automated Control Limits: Calculates UCL, LCL, and center lines using standard formulas
- • Signal Detection: Identifies out-of-control patterns with Western Electric rules
- • Interactive Charts: Interactive visualization with hover details and annotations
- • Moving Range Analysis: Simultaneous monitoring of location and variation
- • Export Capabilities: Generate high-resolution charts for reports and presentations
Analysis Workflow
- Upload individual measurement data with time sequence
- System calculates moving ranges automatically
- Control limits computed using established constants
- Both I-chart and MR-chart displayed simultaneously
- Signal analysis performed with detailed flagging
- Interpretation guide provided
Example Data Layout for I-MR Chart
Individual measurements with moving ranges calculated between consecutive observations. First moving range is blank. Sample Size Recommendation: Minimum 20-25 individual measurements for reliable I-MR control limits - adequate baseline needed for process variability estimation.
This is how your spreadsheet or CSV file should be structured before you upload it. Match the column names, keep one row per observation, and leave the analysis to the platform.