Quality Control Edition

Control charts with detection rules, phases, and stratification Shewhart variable and attribute charts, CUSUM, EWMA, and UWMA time-weighted charts — with WECO, Nelson, and Montgomery detection rules, phases for before-and-after comparison, and stratification by operator, shift, machine, or any factor.

Every chart type, every detection rule, in one package

Most SPC tools cover part of the picture. Some handle Shewhart charts but not time-weighted charts. Some plot the data against control limits but leave you to spot runs, trends, and oscillation patterns by eye. Some offer CUSUM but not attribute charts. The result is that quality teams stitch together multiple tools, transfer data between them, and lose continuity between charting and investigation.

Analyse-it includes Shewhart variable charts (Xbar-R, Xbar-S, I-MR and individual component charts), attribute charts (p, np, c, u), and time-weighted CUSUM, EWMA, and UWMA charts — with WECO, Nelson, and Montgomery detection rules applied to every chart. Phases separate control limits for periods before and after a process change. Stratification overlays a factor onto the chart so that patterns invisible in aggregate data — one shift consistently higher, one machine more variable — become immediately visible.

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What’s included

Monitor continuous data with variable charts

Xbar-R, Xbar-S, Xbar, R, S, I-MR, I, and MR charts. Choose the chart appropriate for your subgroup size and data structure — Xbar-R for subgroups of 2–8, Xbar-S for larger subgroups, I-MR for individual measurements. Control limits calculated from the data or specified from a known standard. Multiple plot styles: point, line, high-low, and box plot.

Track defects and defective units with attribute charts

Shewhart p, np, c, and u charts for pass/fail inspection data, defect counts, and defectives per unit. p and np for proportion or count of defective units in a sample; c and u for defect counts per unit or per inspection. The same detection rules, phasing, and stratification capabilities as variable charts.

Detect small sustained shifts with time-weighted charts

CUSUM (cumulative sum), EWMA (exponentially weighted moving average), and UWMA (uniformly weighted moving average) charts. Where Shewhart charts are designed to detect large, sudden shifts, time-weighted charts accumulate evidence of small, persistent changes in the process mean — such as a reagent degrading gradually or a tool wearing over time.

Flag out-of-control conditions automatically

WECO, Nelson, and Montgomery detection rule sets, or define custom rules. Points beyond control limits, runs above or below the centre line, trends, stratification, and oscillation patterns — all flagged on the chart without manual inspection. Label out-of-control points directly on the chart for reporting and investigation.

Compare performance before and after a process change

Phases with separate control limits for each period. When a process change is introduced — a new supplier, a revised procedure, recalibrated equipment — set a new phase so the limits reflect the new operating conditions rather than being pulled by historical data. See the effect of the change directly on the chart.

Identify hidden sources of variation

Stratify by operator, shift, machine, material lot, or any factor. Colour points on the chart according to the stratification factor so that patterns hidden in aggregate data become visible — such as one operator consistently above the centre line, or greater variability on a particular shift.

Example analyses

See control chart output in detail — Shewhart, CUSUM, EWMA, and attribute charts with detection rules, phases, and stratification — using real datasets you can download and follow along with.

Xbar-R with Montgomery rules
Copper plating thickness, OQ and production phases. Xbar-R chart with Montgomery detection rules, operator stratification, 7 out-of-control signals flagged.

EWMA chart
Copper plating thickness, λ=0.2. EWMA chart with R chart, OQ and production phases. 1 out-of-control signal.

CUSUM chart
Copper plating thickness, h=5, k=0.5. CUSUM chart with R chart, OQ and production phases. No out-of-control signals.

I-MR and attribute charts
Loan costs, supply chain defects, purchase orders. I-MR chart (3 OOC signals), u chart for defects per unit, p chart with Z-score for defective proportion.

Part of the Quality Control & Improvement edition

Control charts are one part of the complete SPC and improvement toolkit. The Quality Control & Improvement edition also includes process capability analysis (Cp, Cpk, Pp, Ppk, Cpm, Z-benchmark) and Pareto analysis, plus the full Standard edition with hypothesis tests, ANOVA, and regression for root cause investigation. See everything in the Quality Control & Improvement edition →

Validated, reliable, trusted for over 30 years

Validated calculations Every statistic tested against published datasets and thousands of internal test-cases. No reliance on Excel’s built-in functions — Analyse-it handles all calculations internally. See how we develop and validate Analyse-it →

Data stays on your PC No cloud processing, no uploads, no third-party access. Your data never leaves your computer — essential when working with proprietary process data, customer specifications, or regulated production records.

Standard Excel workbooks Charts and results are ordinary Excel workbooks. Share with colleagues, send to auditors or customers, archive for quality records — no Analyse-it licence required to view.

No formulas to break Results contain no formulas, so they can’t be accidentally edited or corrupted. The control chart you reported will be exactly what you find when you reopen the workbook.

Technical details

Shewhart variable charts

Xbar-R
Xbar-S
Xbar
R
S
I-MR
I
MR

Shewhart attribute charts

Time-weighted charts

CUSUM (cumulative sum)
EWMA (exponentially weighted moving average)
UWMA (uniformly weighted moving average)

Detection rules

WECO rules
Nelson rules
Montgomery rules
Custom rules

Chart features

Phases with separate control limits per period
Stratification by any factor (colour points)
Label out-of-control points
Control limits from data or specified standard
Plot styles: point, line, high-low, box plot