Based on these attributes and their levels, 48 descriptions of coffee types
were possible (22322). Itwas evidently impossible for respondents
to indicate a preference for 48 product types. Conjoint analysis instead uses
a fractional design, i.e., a systematic selection of a small number out of the full
setofproductprofiles,whilemaintainingthecoincidenceofuncorrelatedlevels
ofdifferentattributesappearingtogether.Thisdesignassures thatanestimateof
the importance of one attribute is unaffected by the estimate of other attributes.
Using Orthoplan of SPSS, a fractional (orthogonal) design of eight product
profiles was generated out of the set of 48 profiles (see Table 2). These eight
product profileswere visually presented and described to informthe respondents
about the attributes. For instance, the fair-trade label was described as
a label on the package indicates that a fair price for the coffee harvest is guaranteed to
the farmers of the South