Six Sigma - Measure Phase

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During Measure Phase the overall performance of the Core Business Process is measured.

There are three important part of Measure Phase.

(1) Data Collection Plan and Data Collection

A data collection plan is prepared to collect required data. This plan includes what type of data needs to be collected, what are the sources of data etc., The reason to collect data is to identify areas where current processes need to be improved.

You collect data from three primary sources: input, process, and output.

  • The input source is where the process is generated.

  • Process data refers to tests of efficiency: the time requirements, cost, value, defects or errors, and labor spent on the process.

  • Output is a measurement of efficiency.

(2) Data evaluation:

At this stage, collected data is evaluated and sigma is calculated. This gives approximate number of defects.

  • A Six Sigma defect is defined as anything outside of customer specifications.

  • A Six Sigma opportunity is the total quantity of chances for a defect.

First we calculate Defects Per Million Opportunities (DPMO) and based on that a Sigma is decided from a predefined table:

                   Number of defects 
DPMO =   ------------------------------------------- x 1,000,000
           Number of Units x Number of opportunities

As stated above, here Number for defects is total number of defects found, Number of Units is the number of units produced and number of opportunities means the number of ways to generate defects.

For example: The food ordering delivery project team examines 50 deliveries and finds out the following:

  • Delivery is not on time (13)

  • Ordered food is not according to the order (3)

  • Food is not fresh (0)

So now DPMO will be as follows:

         13 + 3
DPMO = ----------- x 1,000,000 = 106,666.7
         50 x 3

According to the Yield to Sigma Conversion Table given below 106,666.7 defects per million opportunities is equivalent to a sigma performance of between 2.7 and 2.8.

This is the method used for measuring results as we proceed through a project. This beginning point enables us to locate the cause and effect of those processes and to seek defect point so that the procedure can be improved.

(3) Failure Mode and Effects Analysis - FMEA:

The final segment of the measure phase is called FMEA. This refers to preventing defects before they occur. The FMEA process usually includes rating possible defects, or failures, in three ways:

  • The likelihood that something will go wrong.

  • The ability to detect a defect.

  • The level of severity of the defect.

You may use a rating scale. For example, rate each of these three areas from 1 to 10, with 1 being the lowest FMEA level and 10 being the highest. The higher the level, the more severe the rating. So a high FMEA would indicate the need to devise and implement improved measuring steps within the overall process. This would have the effect of preventing defects. Clearly, there is no need to spend a lot of time on this procedure if the likelihood of a defect is low

Yield to Sigma Conversion Table

Yield %SigmaDefects Per Million Opportunities
99.99976.003.4
99.99955.925
99.99925.818
99.99905.7610
99.99805.6120
99.99705.5130
99.99605.4440
99.99305.3170
99.99005.22100
99.98505.12150
99.97705.00230
99.96704.91330
99.95204.80480
99.93204.70680
99.90404.60960
99.86504.501350
99.81404.401860
99.74504.302550
99.65404.203460
99.53404.104660
99.37904.006210
99.18103.908190
98.93003.8010700
98.61003.7013900
98.22003.6017800
97.73003.5022700
97.13003.4028700
96.41003.3035900
95.54003.2044600
94.52003.1054800
93.32003.0066800
91.92002.9080800
90.32002.8096800
88.50002.70115000
86.50002.60135000
84.20002.50158000
81.60002.40184000
78.80002.30212000
75.80002.20242000
72.60002.10274000
69.20002.00308000
65.60001.90344000
61.80001.80382000
58.00001.70420000
54.00001.60460000
50.00001.50500000
46.00001.40540000
43.00001.32570000
39.00001.22610000
35.00001.11650000
31.00001.00690000
28.00000.92720000
25.00000.83750000
22.00000.73780000
19.00000.62810000
16.00000.51840000
14.00000.42860000
12.00000.33880000
10.00000.22900000
8.00000.09920000


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