The PairWiseCompare website is intended to support the development of quasi-interval measurement scales (for extensive and intensive physical attributes and hypothesized latent attributes) by facilitating the collection of pairwise comparison (c.f. Thurstone) data. Researchers interested in creating such scales will use this website to define the comparison sets and collect response data from participants. The Rasch model can be used to analyse the resulting pairwise comparison data sets and support reseachers as they examine the nature of the construct, estimate positions of comparison items on a quasi-interval measurement scale, assess individual mastery of the construct, or address other related questions.