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Senthil Kumar Ganesan

Is green belt in six sigma prerequisite to get Black belt

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Hi Senthil

Green Belt is a prerequisite for Black Belt training. Green belt forms the basis for mode advanced topics that get covered in Black Belt.

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I hope that you need to known the basic information regarding the Six Sigma. if yes then go to directly do black belt. But not sure about my replies.


Hence some of my friends could get the BB certication.

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Hi Veeranaga


It is like jumping grade 5 and going straight to grade 6. There are some who can cope up with the jump and then there are those who want to take it one step at a time.

Similarly, going directly for Black Belt is possible, but it will involve extra effort from one (brush up the basic knowledge and then do a lot of self study in order to understand the GB concepts as GB concepts will not be covered again in a Black belt course). So even though doable, i do not recommend it as I believe the foundation needs to be strong and GB is the foundation for BB and MBB.

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Hi Mayank,


I have been working in KPO and based on our quality process. we need to calculate the Zigma level for the project based on the project weekly quality scores.


Could you please ensure that the below steps are correct, else help me to identify this.


1) Check the process as incontrol & identify the median, Std Deviation for the attached excel using minitab

2) Using the sigma calcluator with the identified median, Std Deviation and USL "98"

3) Fix the Zst as the sigma for the project

4) publish to process owner




Sigma Level.xlsx

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Dear Prakash


How are weekly quality scores calculated? Provide information on what goes into the Numerator and Denominator.


In my understanding the quality metric (for a KPO industry) is usually Discrete in nature. That means we either calculate defectives or defects. Secondly how is your quality metric being reported out (Defective % or DPU or DPMO). Once you have the answer to these, you can use the Sigma Calculator (shared during the GB session) for Discrete Data and get the Z values. 


We don't use Median for Sigma calculation. Instead we use Mean. 

Mean, Standard Deviation and Specification Limits (LSL and/or USL) are used in case we have continuous data (something that is measured like time, length etc.). In some organizations, quality % is considered as continuous. If that is the case, then your approach can be used. Use the mean quality score for last week, standard deviation in quality scores for last week and LSL as 98% (in quality metric, we usually have a LSL or a minimum quality as USL is 100%).


Glad that you are implementing the learning. Good luck with publishing the Z scores.

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Hi Mayank,


Thanks for detailed infortmation and support to implement.


In our KPO process, we have processed more no of datapoints related to contact person's

1) Name

2) Telphone

3) Email

4) Address

5) Educataion

Based on these, we have collected approx 1000 persons and take 10% sampling audit and derive the quality level from the errors made by the team.

I have attached values are derived from these process and customer doesnt have specify any quality level.

We have fixed in our concern as 98% as LCL.


Please let me explain the way to identify the sigma level. 



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Hi Prakash, 


Good question. Please go through the DPMO method of Sigma Level calculation. You will not need specification limits or control limits for discrete data




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