Multi-vari study

which family of variation is the largest

A sampling plan and chart that shows within-piece, piece-to-piece and time-to-time variation together. Several consecutive parts are measured at several positions, repeated over time, and the family with the largest spread points to where the root cause is.

It is a classic first step of a root cause investigation and of the Shainin approach.

Calculate it

Multi-Vari Chart and Box Plot: Multi-vari chart, families of variation and box plots for root cause work.

Related terms

• Families of variation: positional, cyclical and temporal variation
• Box plot: median, quartiles and outliers of a group