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Subgroup in SPC

Discussion in 'SPC - Statistical Process Control' started by shankar Jadhav, Nov 17, 2015.

  1. shankar Jadhav

    shankar Jadhav Member

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    What will effect of subgroup in SPC study.
     
    shankar Jadhav, Nov 17, 2015
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  2. Miner

    Miner Moderator Staff Member

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    Please be more specific in your query. This is a very broad topic that could consume pages of response.
     
    Miner, Nov 17, 2015
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  3. Bob Doering

    Bob Doering Member

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    It is no so much of a question of what effect the subgroup size has on the study - that is simple: the correct subgroup will generate the most accurate model of the variation. The key question is what subgroup is the best to generate an accurate model of the variation to compare over time. Has a lot to do with the rate and range of the variation you need to capture to ensure an accurate model and therefore accurate conclusions toward action.
     
    Bob Doering, Nov 17, 2015
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  4. Bev D

    Bev D Moderator Staff Member

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    Since the traditional Shewhart charts are tests of homogeneity, the variation captured within the subgroup must also be the variation represented between subgroups.

    As you can see there are various potential responses to the question. a more specific question will enable us to better help you
     
    Bev D, Nov 17, 2015
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  5. reynald

    reynald Member

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    Looks like a classroom question. Simple classroom answer could be: the correct or incorrect sub-grouping can either expose or expose the variation that you want to detect in the first place.
     
    reynald, Nov 18, 2015
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    Chris Glover and Bob Doering like this.