Browsing by Author "Lord, Frederic M."
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item A broad-range tailored test of verbal ability(1977) Lord, Frederic M.Two parallel forms of a broad-range tailored test of verbal ability have been built. The test is appropriate from fifth grade through graduate school. Simulated test administrations indicate that the 25-item tailored test is at least as good as a comparable 50-item conventional test. At most ability levels, the tailored test measures much better. An offer is made to provide upon request item characteristic curve parameters for 690 widely used Cooperative Test items, in order to facilitate research.Item Comparison of IRT true-score and equipercentile observed-score "equatings"(1984) Lord, Frederic M.; Wingersky, Marilyn S.Two methods of ’equating’ tests are compared, one using true scores, the other using equipercentile equating of observed scores. The theory of equating is discussed. For the data studied, the two methods yield almost indistinguishable results.Item Developing a common metric in item response theory(1983) Stocking, Martha L.; Lord, Frederic M.A common problem arises when independent estimates of item parameters from two separate data sets must be expressed in the same metric. This problem is frequently confronted in studies of horizontal and vertical equating and in studies of item bias. This paper discusses a number of methods for finding the appropriate transformation from one metric to another metric and presents a new method. Data are given comparing this new method with a current method, and recommendations are made.Item An investigation of methods for reducing sampling error in certain IRT procedures(1984) Wingersky, Marilyn S.; Lord, Frederic M.The sampling errors of maximum likelihood estimates of item response theory parameters are studied in the case when both people and item parameters are estimated simultaneously. A check on the validity of the standard error formulas is carried out. The effect of varying sample size, test length, and the shape of the ability distribution is investigated. Finally, the effect of anchor-test length on the standard error of item parameters is studied numerically for the situation, common in equating studies, when two groups of examinees each take a different test form together with the same anchor test. The results encourage the use of rectangular or bimodal ability distributions, and also the use of very short anchor tests.Item Some item analysis and test theory for a system of computer-assisted test construction for individualized instruction(1977) Lord, Frederic M.Under given conditions, conventional testing and computer-generated repeatable testing (CGRT) are equally effective for estimating examinee ability; CGRT is more effective than conventional testing for estimating the mean ability level of a group; and CGRT is less effective for estimating ability differences among individuals. These conclusions are drawn from domain-referenced test theory as distinguished from norm-referenced test theory.Item Standard error of an equating by item response theory(1982) Lord, Frederic M.A formula is derived for the asymptotic standard error of a true-score equating by item response theory. The equating method is applicable when the two tests to be equated are administered to different groups along with an anchor test. Numerical standard errors are shown for an actual equating (1) comparing the standard errors of IRT, linear, e and equipercentile methods and (2) illustrating the effect of the length of the anchor test on the standard error of the equating.