Test theories can be divided roughly into two categories. The first is classical test theory, which
dates back to Spearman’s conception of the observed test score as a composite of true and error components,
and which was introduced to psychologists at the beginning of this century. Important milestones in its
long and venerable tradition are Gulliksen’s Theory of Mental Tests (1950) and Lord and Novick’s
Statistical Theories of Mental Test Scores (1968).
The second is item response theory, or latent trait theory, as it has been called until recently. At the
present time, item response theory (IRT) is having a major impact on the field of testing. Models derived
from IRT are being used to develop tests, to equate scores from nonparallel tests, to investigate item
bias, and to report scores, as well as to address many other pressing measurement problems (see, e.g.,
Hambleton, 1983; Lord, 1980). IRT differs from classical test theory in that it assumes a different relation
of the test score to the variable measured by the test. Although there are parallels between models from
IRT and psychophysical models formulated around the turn of the century, only in the last 10 years has
IRT had any impact on psychometricians and test users. Work by Rasch (1980/1960), Fischer (1974), 9
Birnbaum (1968), ivrighi and Panchapakesan (1969), Bock (1972), and Lord (1974) has been especially
influential in this turnabout; and Lazarsfeld’s pioneering work on latent structure analysis in sociology
(Lazarsfeld, 1950; Lazarsfeld & Henry, 1968) has also provided impetus.
One objective of this introduction is to review the conceptual differences between classical test theory
and IRT. A second objective is to introduce the goals of this special issue on item response theory and
the seven papers. Some basic problems with classical test theory are reviewed in the next section. Then,
IRT approaches to educational and psychological measurement are presented and compared to classical
test theory. The final two sections present the goals for this special issue and an outline of the seven
Hambleton, Ronald K & Van der Linden, Wim J. (1982). Advances in item response theory and applications: An introduction. Applied Psychological Measurement, 6, 373-378. doi:10.1177/014662168200600401
Hambleton, Ronald K.; Van der Linden, Wim J..
Advances in item response theory and applications: An introduction.
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