What is stratification?

The Stratification within the quality management is the classification and grouping of the Data into categories that are smaller and have the same characteristics. The purpose of Stratification (Stratification) is to identify the factors cause a problem. To identify those categories which are the most influential on the issue we are considering, we need to use other quality analysis tools such as Pareto Charts or Diagrams Scatter.

Some examples of Stratification in the production of which such categorization:

• Type of damage


• The Cause of the Damage


• Products


• Model


• Machine


• Material (material)


• Man (operators who do it)


• Date of Production


• Supplier (Supplier)


• Work team or Group Work


• The location of the


• Production Shift

The steps of making the Stratification (Stratification)

The steps that are required in the Stratification (Stratification) is as follows:

1. Determine the purpose of the implementation of the Stratification


2. Specifies variables or the criteria that will be grouped


3. Create groups and sub groups (if necessary)


4. Place the factors into the appropriate group or subgroup


5. In order to make the data easier to see, the stratification data better made into the shape of Pareto chart or Scatter Chart.

Examples of cases and how to create Data Groupings (Stratification)

A company that produces DVD Player has a high product failure rate is about 5% (5 units of DVD Player is broken at the time of the production process). Management of the company to form a cluster of quality control (GKM) to resolve the problems it faces. The first step the Working Group identified the cause of this is the GKM main occurrence of failure. Therefore, the gathered data production for last 1 month. From these data a single Stratification or clustering of the data.

The following are the successful data collected by the GKM working group:

No.	Defects	Causes	Responsible
1	Can not Playback	Motor Defects	Supplier
2	Can not Power ON	Wire not soldered	Workmanship
3	Can not Playback	Wire not soldered	Workmanship
4	Can not Playback	Motor Defects	Supplier
5	Can not Power ON	Solder Short	Workmanship
6	Display Dim	LCD Defects	Supplier
7	Display Dim	LCD No solder	Workmanship
8	Can not Playback	Wire not soldered	Workmanship
9	No Sound Output	Connector not soldered	Workmanship
10	Can not Playback	Motor Defects	Supplier
11	Can not Power ON	Solder Short	Workmanship
12	Can not Playback	Missing Wire	Workmanship
13	No Sound Output	Chips are Not soldered	Dipping Machine
14	Display Dim	Solder Short	Workmanship
15	Can not Playback	Wire not soldered	Workmanship
16	No Display	LCD Defects	Supplier
17	No Display	LCD No solder	Workmanship
18	Can not Playback	Solder Short	Workmanship
19	Can not Playback	Missing Component	Workmanship
20	Can not Power ON	Chips are Not soldered	Dipping Machine

From the above data we can make Stratification or clustering of data into 3 categories i.e. based on type of Failure (Defects), the cause of Failure (Causes) or the person in charge (Responsible).

For example

The Company wants to GKM Groups classify data based on person in charge (Responsible) or party of its contribution to the failure of the production of the DVD player, then the data will be sorted so that the data becomes as below:

Responsible	Quantity
Workmanship	13
Supplier	5
Dipping Machine	2

For simplicity in decision making problem solving, Data is then got it into the form of Pareto Chart (how to create a Pareto Chart can be seen in the article: the sense of Pareto Chart and how to make it):

Pareto Chart of the easier we see that the greatest contribution the product failure is due to the problem of "Workmanship" or other workers who led to the failure of the product. The Working Group thus GKM should be able to take appropriate action in order to reduce the problems posed by the workers.