STRATIFICATION | Stratification Definition

Stratification is a statistical technique of breaking down value/data into meaningful categories or classifications.

This is considered one of the basic 7 QC Tools and is extensively used in Problem Solving Techniques such as 8D, PDCA, and Six Sigma.

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Stratification Definition and Meaning

Stratification is a technique or method that can be defined in many ways:

A technique used to analyze and divide a universe of data into homogeneous groups called -Strata.

It involves observing data, splitting them into distinct classes or categories to see a different process for better analysis.

In Stratification, data recording/observation carried out from multiple sources like shifts, machines, days, people, etc.

In other words, it is a method to divide the data into sub-categories and obtain meaningful information to solve a quality problem.

A statistical technique or system of formation of layers or classes or categories to analyze the problem.

Stratification | Stratification definition

Example: Machine wise Stratification.

Rejection data collected from three different machines and date wise trend chart plotted. From the chart, we can see that machine-3 is contributing to high defects/rejection as compare to machine-1. Therefore, the main focus area/source is a machine no. 3 for necessary measures to reduce process variation and rejection level.

When to use Stratification?

When the data come from different sources or conditions, such as data collected from different shifts, machines, people, days, suppliers and population groups, etc.
Used extensively to control and improve the process. Is the process running OK and how long?

How it is carried out ?

It is carried out by splitting process data into distinct layers or sub-groups and understand the different meaningful patterns to analyze and solve problems.