Brand Preference

In a small-scale experimental study of the relation between degree of brand liking and moisture content and sweetness of the product, the results in the data file brand.sav were obtained. Sweetness and moisture content measurements are coded for confidentiality, but the higher the number, the greater the moisture and sugar content. Brand liking was measured on a 100-point scale, in which the higher the number, the more a sample of tasters liked the product.

1. Plot mean preference against moisture content, indicating sweetness level. Does there appear to be any interaction between moisture and sweetness on preference? Does moisture appear to affect preference? If so, how? Does sweetness appear to affect preference? If so, how?
2. Test for the significance of the moisture and sweetness effects, and their interaction. State your conclusions.
3. It appears that the relationship between preference and moisture might be curvilinear. One could fit a quadratic regression to investigate curvilinearity, but we can also write a contrast that will test for it. For simplicity, consider only the low sweetness group. If the relationship between moisture and preference is linear, then the slope of the line segment between the first two MOISTURE levels will be the same as the slope of the line between the 3rd and 4th MOISTURE levels. If these two slopes differ, however, this would indicate curvature in the relationship.
   
   Test the contrast

L = ( ₄₁ –  ₃₁ ) – ( ₂₁ –  ₁₁ )

where the first subscript indicates the moisture level and the second indicates the sweetness level. (This assumes that you have defined the interaction as moisture x sweetness instead of the other way around. Note also that in order to test this contrast you will have to retain the interaction term in your model, whether or not it is significant.)

Do you have convincing evidence of a curvilinear relationship? If so, describe how preference changes with moisture.

Price: $8.2

Solution: The downloadable solution consists of 4 pages, 420 words and 5 charts.
Deliverable: Word Document