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Minimum sample size

Six Sigma – iSixSigma Forums Old Forums General Minimum sample size

This topic contains 16 replies, has 17 voices, and was last updated by  TonyBo 11 years, 2 months ago.

Viewing 17 posts - 1 through 17 (of 17 total)
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  • #49718

    Louise P
    Participant

    I wonder if you can help?
    We are analysing data from an inbound call centre that receives around 25,000 calls per day. To analyse a significant proportion of these, what minimum percentage would you recommend?
    At the moment we have 600 calls from about 3 weeks, but feel this sample size is too small?
    Thanks in advance, Louise

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    #170227

    Quainoo
    Member

    I found a very smart system that will guide you perfectly through this as well as the analysis and how to read it, need more info ? I will be glad to help with directing you to the source, it is a life saver. processanalyzer@yahoo.com

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    #170687

    Bruno Ternon
    Participant

    Could you please direct me to the “source”?  Thanks!
    Kindly,
    Bruno

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    #170784

    Pomara
    Member

    I wonder if you can help?
    We are analysing data from an inbound call centre that receives around 25,000 calls per day. To analyse a significant proportion of these, what minimum percentage would you recommend?
    At the moment we have 600 calls from about 3 weeks, but feel this sample size is too small?
    Thanks in advance, Louise—————————-
    Could you please direct me to the “source”?  Thanks!
    Kindly,
    Bruno————————————————–
    Try this link, call them, they are always there to help.
     http://www.mentorsoftpro.dbar-innovations.com/ or
    http://www.dbar-innovations.com/ 
    Hope this helps,
    Respectfully,
    Vince

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    #170785

    Helper
    Participant

    Hello Louise,
    I have a three page document about how to calculate sample sizes for both Variable Data analysis and Discrete Data analysis.   It is part of our black belt training manual. 
    If you provide me with your email address, I will send it to you.
    Helper

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    #170786

    Ropp
    Participant

    Helper:
    Please send a copy of your Sample Size document.
    Dave
    dmcarter@gmail.com
     

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    #170793

    Ron
    Member

    It Depends:
    Based on some knowledge of call centers you have a large stratification of calls. You did not state your intended goal so I would 1) Stratify the nature ofthe incoming calls, 2)Take your sample from a proportionate representative sample.
    i.e. if you have 10% Technical, 80% informational, 10% Financial use these to select the number of each type to obtain information.
     
    Regarding the number of samples: use the maximum number you can analyze in the time you have to performr this task. More is better.
    If you are looking for a minimum number use a simple software package avaialbe to calculate power and size.
     

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    #170810

    Dillon
    Participant

    To Louise,
     Did the software at Dbar-innovations posted by Vince help you ? Did you try the live test drive and use the analysis tools ? I am curious,
    Thanks,
     Doug

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    #170846

    Greenalgh
    Participant

    Hi Helper thanks for the offer that sounds very useful, my email is louise.palmer@ge.com

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    #170851

    Scott
    Member

    Please send a copy of your Sample Size document. Thanks
    SmithR5@aetna.com

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    #170894

    Swaggerty
    Participant

    Hi Helper,
    Can you please share that we me too? I had posted an article some time back on the same ( in response to another post- I had checked with somebody else, and had come up with 3 different formulas..each of which was right in its own way..but gave different results)
    , so i would appreciate a standard formula.
    My email is george_abraham2003@yahoo.co.uk
    Thanks in adv,
    George

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    #171335

    Digger
    Participant

    If you could, send me a copy of it, too.  My email address is rushing_empire@hotmail.com.  Thanks!

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    #171341

    Amit Jha
    Participant

    Dear Louise,
     
    The sample size that you want to decide will depend on how minutely do you want to  onitor the calls received, in other words what is the margin of error that you are OK to live with, it statistical terms what is the confidence level and confinence interval that you are looking for in your test.
     
    In the given scenario, the thumb rule is to go with 95% confidence level and 98% confidence interval. So you receive 25000*7 calls per week.  So you can monitor 2,369 calls per week.  If working days are 5 then you may monitor 2356 calls per week.
     
    After a given population size, sample size becomes independent.  Therefore you may have seen bevy little decrease in sample size even though thepopulation has reduced majorly.
     
    You may easlity find on the net online sample size calculators.  Read some more articles and also learn about the power of test.
     
    Let me know if I can be of any further help.
     
    Amit

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    #171342

    Marshall
    Member

    If you would be so kind to email the sample size document to me that would be most appreciated
    rob.marshall@bnymellon.com

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    #171924

    leo
    Participant

    I tried the link for mentorsoft and it did not work, the link to http://www.dbar-innovations.com did work. When I got there I discovered it was a software system with a DMAIC Mentoring style analysis system and a tracking program. No info on consulting, but interesting system.

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    #172057

    J
    Member

    Hi Helper, When you get a chance could you send it to me as well.
    quadrisyed@hotmail.com 

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    #172061

    TonyBo
    Member

    Use a sample size calculator..

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