Pareto analysis with two-way comparative charts One-way and two-way comparative Pareto charts — break down defects by shift, operator, machine or product line to identify not just what is failing, but where and why. Merge, reorder and colour bars to focus on the vital few.

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Microsoft Excel with the Analyse-it tab selected, showing a two-way comparative Pareto chart of colorimeter failures for three operators before and after training, each panel with its bars ranked by frequency and a cumulative percentage line, the failure category legend on the right, and the Pareto task pane open. Handwritten notes: Runs inside Excel: every analysis is on the Analyse-it tab; Pareto charts by training and operator: bars in rank order, cumulative line above; Layout: matrix of operator by training; The report is an ordinary Excel worksheet: share it, archive it, open it on any PC with Excel.

See what is failing, and where

Excel’s built-in Pareto chart ranks the categories, draws the cumulative line and stops. No second factor, and no merging of the small categories into one bar. The ranking identifies the vital few — but it does not tell you why those failures occur. The same defect type may be concentrated on one shift, one machine or one operator.

Which categories account for most of the occurrences? Is the dominant defect spread evenly across shifts, or concentrated on one? Does one operator account for a disproportionate share? Did a change between periods reduce the right category?

Pareto chart with cumulative percentage line

Most occurrences come from a few categories. The Pareto chart ranks defect categories by frequency and draws a cumulative percentage line. The cumulative line shows immediately which categories account for most occurrences — such as the three defect types responsible for 80% of rejects on a production line. Build the chart directly from a defect log or inspection data.

  • Pareto chart with cumulative percentage line
Microsoft Excel showing a Pareto chart of 87 colorimeter failures in six categories, the bars ranked by frequency with the cumulative percentage line and its labels above them, and the Pareto task pane open. Handwritten notes: Cumulative frequency line, each point labelled with the running percentage; Bars in rank order, labelled with their frequency; Label bars and the cumulative line.
Colorimeter failures ranked by frequency, with the cumulative percentage line: the first two categories account for three-quarters of the 87 failures.

One-way and two-way comparative Pareto charts

Comparative Pareto charts split each category by a second factor — operator, shift, machine, product line, time period or any factor in the data. A one-way chart compares by one factor, a two-way chart by two. See whether a dominant defect is spread evenly across shifts or concentrated on one, and whether one operator accounts for a disproportionate share. Compare periods to see whether a change reduced the right category.

  • 1-way comparative Pareto chart
  • 2-way comparative Pareto chart
Microsoft Excel showing a two-way comparative Pareto chart: a row of Pareto panels for each of the operators GMH, JDH and SNH, a column for before and after training, each panel with its cumulative percentage line, and the failure category legend, with the Pareto task pane open. Handwritten notes: One Pareto chart per cell: operator by training; Layout: matrix.
Two-way comparative Pareto chart: colorimeter failures for each of three operators, before and after training.

Merged, reordered and colour-coded bars

A chart with twenty categories is harder to act on than one with five plus Other. Merge low-frequency categories into a single “Other” bar to reduce clutter. Reorder bars to group related defect types together when frequency order is not the grouping you need. Colour bars to draw attention to priority areas, or to distinguish subgroups in a comparative chart.

  • Merge bars to reduce clutter of small-frequency categories
  • Reorder bars to highlight specific problems
  • Vary colour of bars to distinguish categories or subgroups
Microsoft Excel showing the two-way comparative Pareto chart of colorimeter failures by operator and training, the legend listing five failure categories including the merged Equipment failure bar, and the Pareto task pane open on the bar options. Handwritten notes: Equipment failure: electrode and light failures merged into one bar, in every chart; Categories merged, reordered and coloured.
Electrode and light failures merged into one Equipment failure bar, and each failure category given its own colour across the comparative chart.

Control charts, capability analysis, hypothesis tests and regression

A Pareto chart shows where to start; the rest of the edition shows whether the change worked. Identify the top defect with Pareto analysis, then set up a control chart on the same data to track whether it improves over time. Run a capability analysis to quantify how far the process is from meeting the specification. Use hypothesis tests and regression from the included Standard edition to confirm root causes and measure the effect of changes.

Example analyses

See Pareto output in detail — comparative charts by operator and training status, with merged categories and colour coding.

Pareto Example 1 p2 3 pages Pareto analysis
Colorimeter downtime before and after training.
Three analyses. A comparative Pareto stratified by three operators and by training status. Then a Pareto for the 87 failures before training and one for the 58 after, each ranking six failure categories with a cumulative line.

Part of the Quality Control & Improvement edition

Pareto analysis is one part of the complete SPC and improvement toolkit. The Quality Control & Improvement edition also includes Shewhart, CUSUM and EWMA control charts with detection rules, phases and stratification. Process capability analysis (Cp, Cpk, Pp, Ppk, Cpm, Z-benchmark) and the full Standard edition, with hypothesis tests, ANOVA and regression, are included as well. See everything in the Quality Control & Improvement edition →

Related guides in the Learn section: Pareto analysis and the 80/20 rule.

Software you can trust

Validated calculations Every statistic tested against the NIST Statistical Reference Datasets, published datasets and thousands of internal test cases. No reliance on Excel’s built-in functions — Analyse-it handles all calculations internally. How Analyse-it is developed and validated →
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 there is nothing to overwrite and no cell reference to break. The control chart you reported will be exactly what you find when you reopen the workbook.

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