Invariant comparisons in affective design
The principle of invariant comparisons is a key concept for verifying whether the measurement of affective responses has been achieved. Invariant comparisons show a valid evidence for the relationship between the mathematical properties on numbers and the properties of the affective characteristic that is measured. An empirical investigation demonstrated that the Rasch probabilistic model can implement invariant comparisons across items with free sample distribution, yielding a solid basis for inference. The research aimed to establish a common metric for comparing affective responses to different packaging characteristics through tactile perception when squeezing containers of everyday products. The results point to a range of compliance from which consumers can infer what kind of product they might obtain from the containers.