Upload a CSV, map your sequence and measured value, and get an Individuals control chart with 3-sigma limits, every Western Electric signal flagged, and a clear in-control verdict. Free.
Free analyses run on up to 10,000 rows. Larger files are randomly sampled to that size — sign up to analyze your full dataset.
Building your control chart...
Sent to — Individuals control chart with 3-sigma limits, flagged special-cause signals, a process summary, R code, and AI insights.
Analyze another fileThe measurements are ordered by the sequence column and plotted as an Individuals (I) chart. The center line is the process mean; the natural process limits are set at three sigma, where sigma is estimated from the average moving range (the mean absolute change between consecutive points, divided by 1.128). A practical subset of the Western Electric / Nelson rules then scans for special-cause signals: a point beyond the limits, nine points on one side of center, six points trending, and two of three points near a limit. If no rule fires, the process is in statistical control.
Use it whenever you have a stream of measurements in order — production runs, daily KPIs, sensor readings, test results — and want to know whether it is stable and predictable or whether something changed.
Not for judging whether output meets a specification (that needs spec limits and a capability study), and less reliable when the data is strongly autocorrelated or comes in natural subgroups.
Built for: Quality engineers, operations analysts, and anyone monitoring a process over time
Typical data source: A spreadsheet or CSV with an ordered sequence and a measured value per row
Any table with an ordering column and a measured value. For example, fill weights by sample:
Minimum 15 rows · Best with 25-500 ordered measurements
Standard-library analysis: an Individuals (I-MR) control chart for a sequence of measurements — the SPC / Six Sigma staple for telling a stable process apart from one throwing special-cause signals. Computes the center line, the 3-sigma natural process limits from the moving range, and runs a practical subset of the Western Electric / Nelson rules to flag out-of-control points. Works on any dataset: map a sequence column (date, batch, or sample order) and the measured value.
Every measurement in order against the center line and 3-sigma limits; colored points are the special-cause signals to investigate.
Which control rules fired and how many points each flagged — the specific patterns that mark an unstable process.
The process at a glance — mean, sigma, control limits, and whether it is in statistical control.
Plain-English interpretation — what the numbers mean, what's significant, and what to do next.
Is my process stable, or did something change?
Map a sequence column and your measured value. You get an Individuals control chart with the center line and 3-sigma natural limits, every special-cause signal flagged by the Western Electric rules, and a clear in-control or out-of-control verdict.
See our FAQ for details on pricing, data privacy, and how the analysis works. Every report includes a Methodology section showing the statistical test, assumptions checked, and diagnostics run.
Run any analysis on your own data — validated R analyses, interactive reports, AI insights, and PDF export.
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