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Decision Rules

The Western Electric (WECO) rules spc, are decision rules used in Statistical Process Control to detect “out-of-control” or non-random conditions. The location of the observations relative to the control chart limits (typically at +-3 standard deviations)...

Cyclical Variation: What It Is and Why It Matters in Six Sigma

Not all patterns in your data mean the same thing. A process that produces more defects on Mondays has a different root cause than one that drifts high every six months. A sales operation that peaks every December is dealing with something different from one that...

Curvature

In mathematics, curvature is any of several strongly related concepts in geometry. Intuitively, it is the amount by which a curve deviates from being a straight line, or a surface deviates from being a plane. In an...

Cpk Explained: Formula, Benchmarks, and How to Improve It

Your process has been running for weeks. The output looks reasonable. But a customer audit is coming, and they want to see your Cpk. Do you know what it is? More importantly, do you know what it means? Cpk — the Process Capability Index — is one of the most commonly...

Correlation Coefficient

A correlation coefficient is a statistical measure that quantifies the degree of correlation between two variables. It provides insights into the strength and direction of the relationship between variables. In many practical scenarios, we encounter data on two or...