# Process sigma Calculation

Six Sigma – iSixSigma Forums Old Forums General Process sigma Calculation

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• #44590

qlychap
Participant

I am willing to Calcullate the efficiency of the process. kindly help me out. Let me explain.
Each and every department in our organisation got a objective that the NC given to them should be closed within a months time. On a sample we started to calculate the process capability of the departments. below is the data on sample of a department

NCR #

objective failed by

NCR011-04-06
27

NCR002-04-06
28

NCR012-04-06
12

NCR013-04-06
12

NCR014-04-06
12

NCR001-04-06
28

NCR017-05-06
67

NCR018-05-06
67

NCR020-05-06
67

NCR016-05-06
10

NCR019-05-06
10

NCR030-06-06
31

NCR031-06-06
31

NCR032-06-06
31

NCR028-06-06
79

NCR029-06-06
79

NCR003-04-06
-6

NCR004-04-06
-6

NCR005-04-06
-6

NCR006-04-06
-6

NCR008-04-06
-6

NCR007-04-06
-6

NCR009-04-06
-6

NCR010-04-06
-7

NCR015-05-06
-4
On calculating the LSL is 1 ; USL is  30; Mean is 22 and SD is 29.23.
How can I quantify the department and how would I emplain to the departments. ? Kinldy help me out

0
#143180

GDS
Participant

QlyChap,
First of all I would calculate your stats on the “Cycle Time” not the delta.
When I run your numbers I get:
mean of 51.5 days
median of 42
stdev of 29.2
Also looking from a perato concept 64% of your “NCs” are late. My next steps would be to do the same analysis by department so you can find the correct X. I would re-communicate the goal (30 days) and start posting the sample results by depatment. I had a project where department were assigned SOPs to review, our target was to have the document reviewed and any changes completed within 45 days, our historical average was 80 days. By making this a KIP for the facuility and posting the cycle times we are currently running at the 30 day mark. Each department had to evaluate there system of review and the changes in order to meet their target.-

0
#143193

Brit
Participant

Post the same data with the total turnaround time, and maybe we can help.  As you have it stated, the data you have in the table is the number of days past 30 (objective failed by).  Looking at the data like that would have only a 1 sided upper spec at 0 days past 30. So, first do that, then we can calculate the capability of meeting between 1 and 30 days.  Based on you data listed, you had 9 out of 25 that beat the goal = 64% defective.  Currently, not a capable process.
What is the result if the NC is not done on time (\$, satisfaction, etc.)?  Please indicate in your next post as well.
When I calculated the mean and standard deviaiton, I got the same thing you did, but wouldn’t use those numbers anyway.  I would use the totoal cycle time it took to get the thing done.

0
#143194

Hans
Participant

I would you assume that you just add a constant of 30 to the defect data in the file to get to the raw data.

0
#143196

Brit
Participant

Sorry – it’s been a long day.

0
#143234

qlychap
Participant

The data given  is not the time taken to close the NC. It is the time taken beyond 30 days to close the NC. Certain numbers would be in -ve which means that the NC is closed before 30 days. There fore total cycle time would be +30 of the “objective failed by”
NC closure on time shows the commitment of the employee and management towards the Quality management system.

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