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Variable Search

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  • #28080

    Jaran S.
    Participant

    1. Do anybody use variable search in your Six Sigma project or your screening DOE?
    2. I think this tools is the best screening DOE technique but, why do most Six Sigma training and DOE books not include this technique in the content?
    3. I want to use variable search with replicates. How to do and how to analyze the design? I think I can analyze by using series of 2 factors full factorial design to find which is the significant factors (main & interaction). Is that correct?
    Please help, advise, criticize or ……….

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    #69579

    AAA
    Participant

    What is variable search?

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    #69602

    galbiati carlo
    Participant

    Everytime I need to find out which few  factors between many are really significant I use ANOVA ( Analysis of Variance ) multifactor approach where after having set up screening desing experiment ( fractional , half-fractional ) I analyse every main and interaction effect . Is this what you stand for ?

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    #69606

    Jaran S.
    Participant

    Screening design (fractional design or Taguchi design) can only find which main effects are significant or can imply some interaction.
    However, when you have many factors (let say 20 factors), if you have significant AB effect without significant A & B effect then you can not find AB effect. Or I can say you will miss any interactions if the factors in interaction terms do not show strong main effects.
    Variable search is the screening DOE technique that can find interactions in that case. It just requires more runs but not too much as factorial design.
     Jaran S.

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    #69615

    Ken K.
    Participant

    Please post a link, or at least reference a text or journal article that describes what you call “variable search”.  Your posts haven’t given much of a clue as to what, specifically, you are talking about.
    I have been using designed experiments for over 15 years and have only heard the term used in the sense of the use of fractional factional screening designs. Are you talking about super-saturated designs?
    Ken K.

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    #69621

    Kim Niles
    Participant

    Keki Bhoti wrote about “variable search” in his book:
    Bhote, Keki and Adi. “World Class Quality – Using Design of Experiments to Make it Happen”. American Management Association. NY. 2000. 
    I need to dig it out to see if this is what you guys are talking about.  I remember either his “variable search” and or “multi-vari” techniques supply approximations of interactions.  I also know he calls these techniques DOE’s even though they may not meet classical definitions as such.
    KN   
     
     

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    #69625

    Jaran S.
    Participant

    As Kim Niles reply is exatly what I mean.
    Jaran S.

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