Trend scoring constructed response items (i.e. rescoring Time A responses at Time B) gives rise to two-way data that follow a product multinomial distribution rather than the multinomial distribution that is usually assumed. Recent work has shown that the difference in sampling model can have profound negative effects on statistics usually used to…

The sample invariant properties of five anchor test equating methods are addressed. Equating results across two sampling conditions--representative sampling and new-form matched sampling--are compared for Tucker and Levine equally reliable linear equating, item response theory true-score equating, and two equipercentile methods. (SLD)

Articles on equating test forms in this issue are reviewed and discussed. The results of these papers collectively indicate that matching on the anchor test does not result in more accurate equating. Implications for research are discussed. (SLD)

The articles in this issue that address the effect of matching samples on ability are reviewed. In spite of these examinations of equating methods and sampling plans, it is still hard to determine a definitive answer to the question of to match or not to match. Implications are discussed. (SLD)

Two independent replications of a sequence of simulations were conducted to aid in the diagnosis and interpretation of equating differences found between representative (random) and matched (nonrandom) samples for three commonly used conventional observed-score equating procedures and one item-response-theory-based equating procedure. (SLD)

Equating two parallel forms of the College Board Biology Achievement Test using three sampling strategies was examined. For each strategy, five equating procedures were studied: Tucker and Levine equally reliable linear equatings; frequency estimation equipercentile equatings; chained equipercentile curvilinear equatings; and three-parameter…

The equating methods and sampling designs used in the empirical studies in this special issue on the use of matched samples for test equating are described. Four requisites for equating are listed, and the invariance of equating functions requisite is identified as the focus of this issue. (SLD)

Combinations of five methods of equating test scores and two methods of selecting samples of students for equating were compared for accuracy, using data from the administration of the Scholastic Aptitude Test to more than 115,000 students. Implications for research and practice are discussed. (SLD)