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Homework Help: Fractional Factorials (Statistics). Design Identification

  1. Aug 7, 2013 #1
    1. The problem statement, all variables and given/known data
    Anand, Bhadkamkar, and Moghe (1995) used a fractional factorial design to determine which of the six possible factors influenced the determination of manganese in cast iron. The six factors and their levels follow:

    A-Titration speed ; Medium ; Fast
    B-Dissolution time ; 20 ; 30
    C-AgNO3 addition ; 20 ; 10
    D-Persulfate addition ; 2 ; 3
    E-Volume HMnO4 ; 100 ; 150
    F-Sodium arsenite ; 0.10 ; 0.15

    I have attached a data table

    X1 is Titration speed
    X2 is Dissolution time

    a) Identify this design

    b) Give the defining interaction or interactions

    2. Relevant equations

    3. The attempt at a solution

    I've read over this material in my textbook and viewed the lecture video that came with it and I'm still quite confused.

    a) is it just asking for:


    The 2 refers to the levels (-1 and +1+

    The 6 refers to the number of factors

    The -3 to how there are 8 rows of data,


    64/8 = 8

    b) I have no idea what it is asking for with the defining interaction or interactions

    My professor sent this email out:

    I = BCDE = -ADE = -ABC = -BDF = -CEF = ABEF = ACDF. Since I am giving you the defining relation, please state the alias structure for main effect A. You need to go through and add A to each part of the defining interaction to determine the answer modulo 2.

    But I'm still confused.

    Any clarification would be appreciated

    Attached Files:

    Last edited: Aug 7, 2013
  2. jcsd
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