The factor structure of wellness: Reexamining theoretical and empirical models underlying the Wellness Evaluation of Lifestyle (WEL) and the Five-Factor Wel

The 5-Factor Wel, the latest version of the Wellness Evaluation of Lifestyle (WEL), was examined using a completely new 3,993-person database. Through exploratory and confirmatory factor analysis with 2 discrete subsets of these data, a new 4-factor solution was identified that provided the best fit for the data and accounted for 30% of the variance

Observed-score equating as a test assembly problem

A set of linear conditions on item response functions is derived that guarantees identical observed-score distributions on two test forms. The conditions can be added as constraints to a linear programming model for test assembly that assembles a new test form to have an observed-score distribution optimally equated to the distribution on an old form. For a well-designed item pool and items fitting the IRT model, use of the model results into observed-score pre-equating and prevents the necessity ofpost hoc equating by a conventional observed-score equating method. An empirical example illustrates the use of the model for an item pool from the Law School Admission Test

An optimization model for test assembly to match observed-score distributions

An optimization model is presented that allows test assemblers to control the shape of the observed-score distribution on a test for a population with a known ability distribution. An obvious application is for item response theory-based test assembly in programs where observed scores are reported and operational test forms are required to produce the same observed-score distributions as long as the population of examinees remains stable. The model belongs to the class of 0-1 linear programming models and constrains the characteristic function of the test. The model can be solved using the heuristic presented in Luecht and T. M. Hirsch (1992). An empirical example with item parameters from the ACT Assessment Program Mathematics Test illustrates the use of the model