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  • Discrete Choice Experiment - Fractonnial factorial design

    Dear collegues,

    As PhD student, I want to set up a Discrete Choice Experiment in a consumers survey. The main objective is to measure consumer willingness to pay for multi-labelled seafood products. Following focus group and expert opinion, my attributes and their corresponding levels will be the following :
    Attributes Level
    Price Market price; +10%; + 20%; +30%
    Labels None; Ecolabel; Health Allegations; Both labels
    Production Method Wild cod; Raised salmon; Wild seabass; raised seabass

    My full factorial desing is composed by 64 attribute combinations (4*4*4). To generate it, i used the following code

    Code:
    matrix attrib = 4,4,4
    genfact, levels (attrib)
    list, separator (4)
    I obtained a table which present the entire combination.

    I therefore have to select a fractonnial factorial design for my survey. To do so, i used the following code:

    Code:
    rename x1 price
    rename x2 labels
    rename x3 species
    
    recode price (1=0) (2=1) (3=2) (4=3)
    recode labels (1=0) (2=1) (3=2) (4=3)
    recode species (1=0) (2=1) (3=2) (4=3)
    
    ******* Test de Defficient *******
    
    matrix b = J(1,9,0)
    dcreate i.price i.labels i.species, nalt(2) nset(12) bmat(b)
    I aim to propose to each individual in my survey to choose between two options and one output option. Each individual will have to do this operation three times.


    I don't understand how to select the fractionnal design with the higher Defficenty ... Each time I run the last two lines of my code, the Defficienty score changes. I am confused about the procedure to follow. And I haven't introduced the opt-out yet for the moment in my design ...


    Sorry for these questions, I am just starting to get interested in these issues of DCE.

    If you want more information to clarify my position, i remain available

    Best Regards

    Jean-François DEWALS

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