Factor analytic methods to evaluate scales
Under construction (I am still writing this)
In most of applied research we use factor analysis for exploratory purposes (to know which variables hang
with which variables to form a scale). However, we also use factor models to evaluate test products, such as student
achievement test. Under the NCLB legislation (No Child Left Behind), there are a lot of efforts in this area.
For example, state authorities need to report to the federal government regarding the validity of sub-scales.
Most basically we use two different factor models. One model ignores the fact that test items have
separate sub-components (e.g., all test items contribute to create a math score). The other model