Example 1. Polar and Dimensional Continuum Models. Polar models (left) define extreme cases (the different types) and can place individual performances along a continuum connecting them. Dimensional models (right) define relevant features of performances (the different dimensions) and can place individual performances in a multidimensional space according to their values for each dimension. Typological questions motivate both kinds of models: for polar models, one must define the poles, and for dimensional models, one must define the relevant dimensions.