Browsing by Subject "tests"
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Item The Composition Of Normative Groups And Diagnostic Decision Making: Shooting Ourselves In The Foot(2006-08) Pena, Elizabeth D.; Spaulding, Tammie J.; Plante, Elena; Pena, Elizabeth D.Purpose: The normative group of a norm-referenced test is intended to provide a basis for interpreting test scores. However, the composition of the normative group may facilitate or impede different types of diagnostic interpretations. This article considers who should be included in a normative sample and how-this decision must be made relative to the purpose for which a test is intended. Method: The way in which the composition of the normative sample affects classification accuracy is demonstrated through a test review followed by a simulation study. The test review examined the descriptions of the normative group in a sample of 32 child language tests. The mean performance reported in the test manual for the sample of language impaired children was compared with the sample's norms, which either included or excluded children with language impairment. For the simulation, 2 contrasting normative procedures were modeled. The first procedure included a mixed group of representative cases (language impaired and normal cases). The second procedure excluded the language impaired cases from the norm. Results: Both the data obtained from test manuals and the data simulation based on population characteristics supported our claim that use of mixed normative groups decreases the ability to accurately identify language impairment. Tests that used mixed norms had smaller differences between the normative and language impaired groups in comparison with tests that excluded children with impairment within the normative sample. The simulation demonstrated mixed norms that lowered the group mean and increased the standard deviation, resulting in decreased classification accuracy. Conclusions: When the purpose of testing is to identify children with impaired language skills, including children with language impairment in the normative sample can reduce identification accuracy.Item Letter to H.B. Stenzel from Duncan McConnell on 1944-01-28(1944-01-28) McConnell, DuncanItem A Study of Motor Oils Sold in Texas and Review of Motor Oils Specifications(University of Texas at Austin, 1936-12-01) University of Texas at AustinItem X-Ray And Optical Flux Ratio Anomalies In Quadruply Lensed Quasars. II. Mapping The Dark Matter Content In Elliptical Galaxies(2012-01) Pooley, David; Rappaport, Saul; Blackburne, Jeffrey A.; Schechter, Paul L.; Wambsganss, Joachim; Pooley, DavidWe present a microlensing analysis of 61 Chandra observations of 14 quadruply lensed quasars. X-ray flux measurements of the individual quasar images give a clean determination of the microlensing effects in the lensing galaxy and thus offer a direct assessment of the local fraction of stellar matter making up the total integrated mass along the lines of sight through the lensing galaxy. A Bayesian analysis of the ensemble of lensing galaxies gives a most likely local stellar fraction of 7%, with the other 93% in a smooth, dark matter component, at a mean impact parameter R(c) of 6.6 kpc from the center of the lensing galaxy. We divide the systems into smaller ensembles based on R(c) and find that the most likely local stellar fraction varies qualitatively and quantitatively as expected, decreasing as a function of R(c).