Guides

Explanations of the statistical methods used in quality control, with calculation steps.

• Process Capability (Cpk) Calculator What Is Cpk? Formula, Worked Example and Target Values

  What the process capability index Cpk means, how to calculate it step by step with a worked example, common targets like 1.33 and 1.67, and Excel formulas.

• Process Capability (Cpk) Calculator Cp vs Cpk vs Pp vs Ppk: Differences and Formulas

  The difference between Cp, Cpk, Pp and Ppk explained through within-subgroup and overall standard deviation, with a worked example and guidance on which to use.

• Correlation Analysis Tool Correlation Coefficient: Formula, Example and How to Read Scatter Plots

  What the correlation coefficient r means, how to calculate it with a worked example, how to judge its strength, and common pitfalls when reading scatter plots.

• X-bar and R Control Chart X-bar and R Chart: Control Limits, Example and Interpretation

  How an X-bar and R chart works: control limit formulas and constants, a worked example, how to spot out-of-control patterns, and how to build one in Excel.

• X-MR Control Chart (Individuals and Moving Range) I-MR Chart (X-MR Chart): Moving Range, Control Limits and Example

  How an I-MR (X-MR) chart works for individual measurements: moving range, control limit formulas, a worked example, and when to use it instead of X-bar and R.

• Pareto Chart Pareto Chart: How to Make One and Calculate Cumulative Percentages

  What a Pareto chart is, how to make one step by step, how to calculate cumulative percentages with an example, and how to find the vital few problems to tackle.

• Histogram Tool Histogram: How to Make One, Choose Bins and Read the Shape

  What a histogram shows, how to make one and choose the number and width of bins, how to read common shapes, and how to compare the data with specification limits.