Indeed, assessment may be better than compared with a conventional test. Griffin's research has found that the tasks on his platform do not exhibit the between nation bias (or Differential Item Functioning) that questions on the standardised, international PISA assessment purportedly suffer from (Kreiner & Christensen, 2014). They are also robust to differences in background language (Vista, Care and Griffin, 2014). The fact that assessment takes a back seat here begs the following question. Of what real worth is the psychometric modelling in the background?

Bayesian methods can be used in general data-analytic models, in psychometric models, and in models of mind. In all three applications, there is Bayesian estimation of parameter values in a model. What differs between models is the source of the data and the meaning (semantic referent) of the parameters, as described in the diagram below: As an example of a generic data-analytic model, consider data about ice cream sales and sleeve lengths, measured at different times of year. A linear regression model might show a negative slope for the line that describes a trend in the scatter of points. But the slope does not necessarily describe anything in the processes that generated the ice cream sales and sleeve lengths.