Reasoning Principles and Formal Measurement Models  Those
involved in educational and psychological measurement must deal
with a number of issues that arise when one assumes a
probabilistic relationship between the observations made of a
learner and the learner’s underlying cognitive constructs. The
essential idea is that statistical models can be developed to
predict the probability that people will behave in certain ways
in assessment situations, and that evidence derived from
observing these behaviors can be used to draw inferences about
students’ knowledge, skills, and strategies (which are not
directly observable).2 In assessment, aspects of students’
knowledge, skills, and strategies that cannot be directly
observed play the role of “that which is to be explained”
—generally referred to as “cognition” in Chapter 2 and more
specifically as the “construct” in this chapter. The constructs
are called “latent” because they are not directly observable.
The things students say and do constitute the evidence us