bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymorphic crystal structures of an all‐AT DNA dodecamer
Authors: Acosta‐Reyes Francisco J. , Subirana Juan A. , Pous Joan , Sánchez‐Giraldo Raquel , Condom Núria , Baldini Roberto , Malinina Lucy , Campos J. Lourdes
Published: September 2014

In this work, we explore the influence of different solvents and ions on the crystallization behavior of an all‐AT dodecamer d(AATAAATTTATT)2 In all cases, the oligonucleotides are found as continuous columns of stacked duplexes. The spatial organization of such columns is variable; consequently we have obtained seven different crystal forms. The duplexes can be made to crystallize in either parallel or crossed columns. Such versatility in the formation of a variety of crystal forms is characteristic for this sequence. It had not been previously reported for any other sequence. In all cases, the oligonucleotide duplexes have been found to crystallize in the B form. The crystallization conditions determine the organization of the crystal, although no clear local interactions have been detected. Mg2+ and Ni2+ can be used in order to obtain compact crossed structures. DNA–DNA interactions in the crystals of our all‐AT duplexes present crossovers which are different from those previously reported for mixed sequence oligonucleotides. Our results demonstrate that changes in the ionic atmosphere and the crystallization solvent have a strong influence on the DNA–DNA interactions. Similar ionic changes will certainly influence the biological activity of DNA. Modulation of the crystal structure by ions should also be explored in DNA crystal engineering. Liquid crystals with a peculiar macroscopic shape have also been observed. © 2014 Wiley Periodicals, Inc. Biopolymers 103: 123–133, 2015.
Stimuli‐Responsive Supramolecular Interfaces for Controllable Bioelectrocatalysis
Authors: Wan Pengbo , Chen Xiaodong
Published: September 2014

Inspired by natural biochemical promotion and inhibition of electron‐transport processes in response to real‐life physical/chemical stimuli, artificial signal‐triggered bioelectrocatalysis and modulation of the electron‐transfer processes of redox biomolecules are vitally important for understanding electron‐transport pathways in bioelectrochemical systems and for mimicking the dynamic properties of sensitive biochemical reactions in real bioprocesses. Recently, the reversible activation and deactivation of bioelectrocatalysis by external stimuli on functional electrodes integrated with redox enzymes has been established, especially at stimuli‐responsive supramolecular interfaces. Potential applications in various research fields include controllable biofuel cells, bioelectronic devices, stimuli‐responsive biosensors, energy transduction, information storage, and data processing. This Minireview aims to summarize the current state‐of‐the‐art knowledge on various controllable bioelectrocatalysts from diverse functional interfaces formed by supramolecular interactions and supramolecular assemblies. The role of the assembled interface is highlighted, and the electrochemical kinetics during “on” and “off” states of bioelectrocatalysis is discussed. Finally, possible strategies for the future design of stimuli‐responsive bioelectrocatalysts integrated with multifunctional supramolecular interfaces are presented.
Mechanisms for the Breakdown of Halomethanes through Reactions with Ground‐State Cyano Radicals
Authors: Farahani Pooria , Maeda Satoshi , Francisco Joseph S. , Lundberg Marcus
Published: September 2014

One route to break down halomethanes is through reactions with radical species. The capability of the artificial force‐induced reaction algorithm to efficiently explore a large number of radical reaction pathways has been illustrated for reactions between haloalkanes (CX3Y; X=H, F; Y=Cl, Br) and ground‐state (2Σ+) cyano radicals (CN). For CH3Cl+CN, 71 stationary points in eight different pathways have been located and, in agreement with experiment, the highest rate constant (108 s−1 M−1 at 298 K) is obtained for hydrogen abstraction. For CH3Br, the rate constants for hydrogen and halogen abstraction are similar (109 s−1 M−1), whereas replacing hydrogen with fluorine eliminates the hydrogen‐abstraction route and decreases the rate constants for halogen abstraction by 2–3 orders of magnitude. The detailed mapping of stationary points allows accurate calculations of product distributions, and the encouraging rate constants should motivate future studies with other radicals.
Simultaneous separation of ergot alkaloids by capillary electrophoresis after cloud point extraction from cereal samples
Authors: Felici Emiliano , Wang Chien C. , Fernández Liliana P. , Gomez María R.
Published: September 2014

A new and sensitive analytical methodology for ergot alkaloids (EA) determination from cereal samples based on cloud point extraction (CPE) prior to CE‐UV absorbance was developed. The methodology involves extraction under acid conditions and subsequent preconcentration by applying a simple, rapid and environmentally friendly low volume surfactant extraction procedure. After extraction, CE analysis was carried out by performing dilutions on preconcentrated surfactant rich phase, achieving a single peak or simultaneous alkaloids determination. A real preconcentration factor of 22 of total EA was obtained, demonstrating the efficiency of this methodology. The limits of detection were 2.6 and 2.2 μg/kg for ergotamine and ergonovine, respectively. Validation procedure revealed suitable linearity, accuracy and precision. The average extraction and clean‐up recoveries were compared with the theoretical values and were better than 92%. This method was successfully applied to the determination of EA in different varieties of commercial flour samples, two grain samples and one of the leading brands cereal‐based product for infant feeding. The high sensitivity achieved for EA determinations in real samples suggests CPE procedure as an interesting approach to improve CE‐UV visible detection limits. Moreover, the whole process could be considered as a contribution to green chemistry because nonorganic solvents were involved, demonstrating its great potential over conventional techniques.
3D Insulator‐based dielectrophoresis using DC‐biased, AC electric fields for selective bacterial trapping
Authors: Zellner Phillip , Shake Tyler , Hosseini Yahya , Nakidde Diana , Riquelme Maria V. , Sahari Ali , Pruden Amy , Behkam Bahareh , Agah Masoud
Published: September 2014

Insulator‐based dielectrophoresis (iDEP) is a well‐known technique that harnesses electric fields for separating, moving, and trapping biological particle samples. Recent work has shown that utilizing DC‐biased AC electric fields can enhance the performance of iDEP devices. In this study, an iDEP device with 3D varying insulating structures analyzed in combination with DC biased AC fields is presented for the first time. Using our unique reactive ion etch lag, the mold for the 3D microfluidic chip is created with a photolithographic mask. The 3D iDEP devices, whose largest dimensions are 1 cm long, 0.18 cm wide, and 90 μm deep are then rapidly fabricated by curing a PDMS polymer in the glass mold. The 3D nature of the insulating microstructures allows for high trapping efficiency at potentials as low as 200 Vpp. In this work, separation of Escherichia coli from 1 μm beads and selective trapping of live Staphylococcus aureus cells from dead S. aureus cells is demonstrated. This is the first reported use of DC‐biased AC fields to selectively trap bacteria in 3D iDEP microfluidic device and to efficiently separate particles where selectivity of DC iDEP is limited.
Surface modification of PDMS microfluidic devices by controlled sulfuric acid treatment and the application in chip electrophoresis
Authors: Gitlin Leonid , Schulze Philipp , Ohla Stefan , Bongard Hans‐Josef , Belder Detlev
Published: September 2014

Herein, we present a straightforward surface modification technique for PDMS‐based microfluidic devices. The method takes advantage of the high reactivity of concentrated sulfuric acid to enhance the surface properties of PDMS bulk material. This results in alteration of the surface morphology and chemical composition that is in‐depth characterized by ATR‐FTIR, EDX, SEM, and XPS. In comparison to untreated PDMS, modified substrates exhibit a significantly reduced diffusive uptake of small organic molecules while retaining its low electroosmotic properties. This was demonstrated by exposing the channels of a microfluidic device to concentrated rhodamine B solution followed by fluorescence microscopy. The surface modification procedure was used to improve chip‐based electrophoretic separations. Separation efficiencies of FITC‐labeled amines/amino acids obtained in treated and untreated PDMS‐devices as well as in glass chips were compared. We obtained higher efficiencies in H2SO4 treated PDMS chips compared to untreated ones but lower efficiencies than those obtained in commercial microfluidic glass devices.
Vegetation turnover in a braided river: frequency and effectiveness of floods of different magnitude
Authors: Surian Nicola , Barban Matteo , Ziliani Luca , Monegato Giovanni , Bertoldi Walter , Comiti Francesco
Published: September 2014

This work addresses the temporal dynamics of riparian vegetation in large braided rivers, exploring the relationship between vegetation erosion and flood magnitude. In particular, it investigates the existence of a threshold discharge, or a range of discharges, above which erosion of vegetated patches within the channel occurs. The research was conducted on a 14 km long reach of the Tagliamento River, a braided river in north‐eastern Italy. Ten sets of aerial photographs were used to investigate vegetation dynamics in the period 1954–2011. By using different geographic information system (GIS) procedures, three aspects of geomorphic‐vegetation dynamics and interactions were addressed: (i) long‐term (1954–2011) channel evolution and vegetation dynamics; (ii) the relationship between vegetation erosion/establishment and flow regime; (iii) vegetation turnover, in the period 1986–2011. Results show that vegetation turnover is remarkably rapid in the study reach with 50% of in‐channel vegetation persisting for less than 5–6 years and only 10% of vegetation persisting for more than 18–19 years. The analysis shows that significant vegetation erosion is determined by relatively frequent floods, i.e. floods with a recurrence interval of c. 1–2.5 years, although some differences exist between sub‐reaches with different densities of vegetation cover. These findings suggest that the erosion of riparian vegetation in braided rivers may not be controlled solely by very large floods, as is the case for lower energy gravel‐bed rivers. Besides flow regime, other factors seem to play a significant role for in‐channel vegetation cover over long time spans. In particular, erosion of marginal vegetation, which supplies large wood elements to the channel, increased notably over the study period and was an important factor for in‐channel vegetation trends. Copyright © 2014 John Wiley & Sons, Ltd.
STATUS OF RESEARCH ON ITEM CONTENT AND DIFFERENTIAL PERFORMANCE ON TESTS USED IN HIGHER EDUCATION
Authors: Boldt Robert F.
Published: September 2014

“Outlier studies” identify items for which extreme differences in performance by contrasting groups occur; these extreme items are the “outliers” referred to. Review of the studies conducted on tests receiving major use in higher education reveals that though one cannot make a priori classifications of outliers with confidence, one can with reasonable confidence predict the relatively advantaged group for many verbal items if they subsequently prove to be outliers as follows: aesthetic‐philosophical, human relations or female oriented content relatively favors females as opposed to males; practical affairs, science or male oriented content relatively favors males as opposed to females; science content relatively favors whites as opposed to blacks. For test content that varies in the degree of relatedness to minorities, one would predict a relative advantage for those outliers that are most related to minorities. The magnitude of the differences found is not large; perhaps larger differences would be found if classifications other than race and sex, which are the most common, were used. It has been found that differences in cultural or national origin produce larger discrepancies in item difficulty than differences in race or sex of essentially native American groups.
INTERPERSONAL COMPETENCE, SOCIAL INTELLIGENCE, AND GENERAL ABILITY
Authors: Stricker Lawrence J.
Published: September 2014

The goal of this study was to appraise the construct validity of a videotape‐based situational test, the Interpersonal Competence Instrument (ICI), specifically its convergent validity with regard to other measures of social intelligence as well as its discriminant validity with respect to indexes of general ability. The ICI was administered to college students (fraternity and sorority members, and dormitory residents) along with a battery of other devices: self‐rating, peer rating, and inventory measures of social intelligence and general ability; objective tests of major components of social intelligence and general ability; and control measures. Five factors emerged in a factor analysis of the measures: general ability, age, sex, halo, and distance to the video receiver. The ICI Judgments–Accuracy score defined the general ability factor and had a borderline loading on the age factor; the ICI Replies–Effectiveness score did not appear on any factor. The Judgments–Accuracy score seems to be tapping general ability to some extent, whereas what the Replies–Effectiveness score is assessing cannot be determined at all.
ATTEMPTS AT DEFINING INTERPERSONAL COMPETENCIES
Authors: Baird Leonard L.
Published: September 2014

This review was intended to identify generic skills in interpersonal relations and to examine the implications of research for attempts to assess these skills. Using a developmental framework, three areas of research were reviewed: the social development of children and adolescents, clinical studies of interpersonal competence, and studies of effective leadership. Six skills appeared in this literature: use of basic social forms, common interactions with others, constructive assertiveness, internal monitoring, emotional expression, and the coordination of group activities.
IMPLICATIONS OF COGNITIVE THEORY FOR INSTRUCTION IN PROBLEM SOLVING
Authors: Frederiksen Norman
Published: September 2014

Cognitive theories of problem solving and suggestions made by cognitive psychologists regarding how to teach problem solving are reviewed. Theories and suggestions from creativity research are also considered. The results are summarized in a description of how high levels of proficiency in problem solving are acquired and how problem solving skills might best be taught, keeping in mind a distinction between well and ill‐structured problems. The need for practice materials is discussed, and some desirable qualities of such materials are suggested. Finally, several unresolved issues regarding instructional methods are considered.
SUMMARIES OF STUDIES INVOLVING THE TEST OF ENGLISH AS A FOREIGN LANGUAGE, 1963–1982
Authors: Hale Gordon A. , Stansfield Charles W. , Duran Richard P.
Published: September 2014

This set of 82 summaries is based on papers written between 1963 and 1982 concerning TOEFL. The papers summarized consist primarily of reports of research involving TOEFL. Also included are a few descriptive papers, which are summarized here to provide a perspective on the history and development of the test. The methods and criteria by which papers were identified for inclusion, as well as a scheme for classification of the papers, are presented in the Introduction.
STATISTICS IN ANTITRUST LITIGATION
Authors: King Benjamin F.
Published: September 2014

The antitrust laws were made to discourage business firms from improper use of economic power. They were intended to keep markets competitive, and to ensure that the behavior of businesses toward other firms, as well as toward consumers, is fair. Cases brought under the antitrust laws involve price‐fixing, improper allocation, control of production, resale price maintenance, tying arrangements, and price discrimination, among other specific practices that may have adverse effects on competition in the marketplace. These cases often fall in the category of complex litigation. Because much of the complexity results from issues of measurement, estimation, and inference under uncertainty, attorneys may hire statisticians as consultants or expert witnesses. This paper deals with the role of the statistician as a consultant or expert witness in cases of antitrust litigation.
TEST SCORE CHANGES ON THE GRE GENERAL (APTITUDE) TEST
Authors: Powers Donald E. , Clark Mary Jo , Grandy Jerilee
Published: September 2014

In terms of the numbers of examinees involved, test repetition is a significant phenomenon in standardized admission testing. Although it is readily acknowledged that those who repeat admissions tests are a self‐selected group of test takers, there are continuing questions about the bases on which examinees decide to retake a test.

Through a survey of examinees who had repeated the GRE General (Aptitude) Test, this study documents some of the factors involved in GRE test takers' decisions to repeat the test and examines the relationships of these factors to test score changes. Implications are drawn for advising examinees who contemplate retaking the GRE as well as graduate admissions staff who are confronted with multiple test scores.
TOEFL FROM A COMMUNICATIVE VIEWPOINT ON LANGUAGE PROFICIENCY: A WORKING PAPER
Authors: Duran Richard P. , Canale Michael , Penfield Joyce , Stansfield Charles W. , Liskin‐Gasparro Judith E.
Published: September 2014

This report examines the content characteristics of the Test of English as Foreign Language (TOEFL) from a communicative viewpoint based on current theory in applied linguistics and language proficiency assessment. After a review of relevant literature, the authors developed and applied a four‐part operational framework for analyzing the communicative characteristics of a language proficiency test. The first component of this framework consists of the grammatical, sociolinguistic, and discourse competencies required by test tasks. The second component consists of eight factors that could influence test performance. The third component consists of judgements of the relevance of the content of test items to academic and social language use. The final component relates the langauge and language tasks appearing in TOEFL items and sections to a criterion‐referenced scale of language proficiency. In this case, the Interagency Language Roundtable scale was used. Finally, the report discusses test design features that might improve the quality of language proficiency tests.
THE IMPACT OF SELF‐STUDY ON GRE TEST PERFORMANCE
Authors: Swinton Spencer S. , Powers Donald E.
Published: September 2014

The study reported here was intended to “round out” the GRE Board's continuing study of special test preparation for the GRE General Test by providing information that was previously unavailable on the effects of one kind of special test preparation–self‐test‐familiarization for the verbal and quantitative sections of the test and for the revised analytical portion.

The impact of receiving, and of being encouraged to study, the newly expanded GRE Information Bulletin and copies of disclosed forms of the GRE General Test was investigated in an experimental design in which randomly selected samples of test takers were encouraged to prepare in various ways for the test.

In a previous similar study of the analytical section of the test, self‐study was found to improve performance on two analytical item types that were subsequently removed from the test. In the present study, no practically significant effects were detected for the verbal, quantitative, or revised analytical sections of the test.
RELATIONSHIP OF ADMISSION TEST SCORES TO WRITING PERFORMANCE OF NATIVE AND NONNATIVE SPEAKERS OF ENGLISH
Authors: Carlson Sybil B. , Bridgeman Brent , Camp Roberta , Waanders Janet
Published: September 2014

Four writing samples were obtained from 638 applicants for admission to U.S. institutions as undergraduates or as graduate students in business, engineering, or social science. The applicants represented three major foreign language groups (Arabic, Chinese, and Spanish), plus a small sample of native English speakers. Two of the writing topics were of the compare and contrast type and the other two involved chart and graph interpretation. The writing samples were scored by 23 readers who are English as a second language specialists and 23 readers who are English writing experts. Each of the four writing samples was scored holistically, and during a separate rating session two of the samples from each student were assigned separate scores for sentence‐level and discourse‐level skills. Representative subsamples of the papers also were scored descriptively with the Writer's Workbench computer program and by graduate‐level subject matter professors in engineering and the social sciences.

In addition to the writing sample scores, TOEFL scores were obtained for all students in the foreign sample. GRE General Test scores were obtained for students in the U.S. sample and for a subsample of students in the foreign sample. Students in the U.S. sample also took a multiple‐choice measure of writing ability.

Among the key findings were the following: 1) holistic scores, discourse‐level scores, and sentence‐level scores were so closely related that the holistic score alone should be sufficient; 2) correlations among topics were as high across topic types as within topic types; 3) scores of ESL raters, English raters, and subject matter raters were all highly correlated, suggesting substantial agreement in the standards used; correlations and factor analyses indicated that scores on the writing samples and TOEFL were highly related, but that each also was reliably measuring some aspect of English language proficiency that was not assessed by the other; and (5) correlations of holistic writing sample scores with scores on item types within the sections of the GRE General Test yielded a pattern of relationships that was consistent with the relationships reported in other GRE studies.
THE TWO‐PREDICTOR VALIDITY CURVE
Authors: Dorans Neil J. , Kulick Edward
Published: September 2014

A visual display known as the two‐predictor validity curve is introduced. Derivations are presented for the general case. Then, for illustrative purposes the two predictors are taken to be SAT‐V (V) and SAT‐M (M), and the criterion of interest is the first year college grade point average (FYA). The two‐predictor validity curve, in this case SAT V&M, allows one to assess the relative importance of SAT‐V in relation to SAT‐M for predicting the criterion of interest. When several V&M curves are placed on a single page, comparisons across gender can be made and trends across time can also be studied. Several illustrations using SAT data are presented.
STUDENT CHANGE, PROGRAM CHANGE: WHY THE SAT SCORES KEPT FALLING
Authors: Turnbull William W.
Published: September 2014

The first leg of the Scholastic Aptitude Test (SAT) score decline occurred mainly in the 1960s. It seemed to be explained fairly satisfactorily by the evidence that the composition of the test‐taking group had changed to include a larger proportion of students with relatively low‐developed ability, mirroring the increased holding power of education for teenagers. In studies made during the 1970s, no comparable underlying change was found to explain the second (mainly 1970s) segment of the decline, which was ascribed instead to a complex of factors—“pervasive influences”—in both school and society.

In this study, the importance of pervasive societal influences on student learning is not in dispute. A variety of data suggests, however, that the increase in school retention rates of poorly prepared students and the resulting heterogeneity of the senior high school population is a unifying explanatory variable for the second leg of the decline as well as the first. The argument is that several of the “pervasive influences” invoked to explain the continuation of the decline in the 1970s are best understood as adaptive responses of the schools to the appearance of a greater diversity of students in senior high school. These responses, which in combination represent a reduction in the demand level of the school program, included grade inflation, proliferation of electives, textbook simplification, and reduction in homework assignments. Students also chose fewer academic and more vocational and general courses. It is hypothesized that the continuation of the decline in the 1970s was, in substantial part, the direct consequence of those school‐related changes and thus was a delayed, indirect consequence of the compositional shift.

The two declines seem to have been reciprocal rather than unrelated. Student changes begat program changes, and each new condition in its turn led to lower scores. The paradigm helps to explain why high scores became scarcer in the 1970s, why the scores of students with high class rank continued to drop while those of students with lower class standing stabilized or turned up, and why the pervasive factors seemed to affect only the senior high school students.

This report suggests that the academic demand level of the schools probably stopped falling in the late 1970s, that 1980 marked a significant turning point, and that the recent slight upturn in SAT scores marks the beginning of a positive trend rather than a pause before a continuation of the drop.
THE BUDDHA AND THE COMPUTER: CAREER GUIDANCE IN TAIWAN
Authors: Katz Martin R.
Published: September 2014

Career decision making in Taiwan is examined in the context of a society undergoing dynamic change as modern entrepreneurial values are accommodated in a cherished traditional culture. Recommendations are made on the following topics: rationale for guidance, model of career decision making, individual assessment, development of occupational information, linkages between individual characteristics and occupational attributes, strategy and algorithm for career decision making, testing, and counselor preparation.
EXPLORATION OF CAUSES OF BIAS IN TEST ITEMS
Authors: Scheuneman Janice
Published: September 2014

Although the study of item bias has been an active area of research for the past few years, little progress has been made in understanding what factors in a test might create bias. To advance this understanding, a number of hypotheses were developed concerning elements of the items that might affect the performance of Blacks and Whites differently. The elements investigated were characteristics that would be common to several items that otherwise measured different concepts or content.

Seven general hypotheses were developed and tested in the form of 16 specific hypotheses, most with five or six items. For purposes of this study, items were developed in pairs, with a hypothesized element present in one item and missing or modified in the other. The item pairs were assembled into two separate sections and administered as part of the Graduate Record Examinations General Test. Pairs of test sections were developed for each of the three areas tested in the General Test: verbal, quantitative, and analytical ability. These sections were spiralled for administration to yield randomly equivalent groups of examinees.

The 16 specific hypotheses were evaluated separately using log linear analyses. Results showed that 10 of the 16 hypotheses showed interactions between group membership and item version indicating a differential effect of the manipulation on the performance of Black and White examinees. Eight of these hypotheses were also analyzed for item bias at the individual item level, using a procedure based on item response theory.

The conclusion was that item manipulations of the type hypothesized did have a differential effect on the performance of Black and White examinees. The complexity of the effects, however, suggested that other uncontrolled factors affecting performance were also operating. A number of suggestions for future research based on these results were provided.
A SURVEY OF ACADEMIC DEMANDS RELATED TO LISTENING SKILLS
Authors: Powers Donald E.
Published: September 2014

A literature review was conducted in order to identify various parameters underlying listening comprehension. The results of this review were used as a basis for a survey of faculty in six graduate fields as well as undergraduate English faculty. The purpose of the survey was to (a) obtain faculty perceptions of the importance to academic success of various listening skills and activities, (b) assess the degree to which both native and nonnative speakers experience difficulties with these skills or activities, and (c) determine faculty views of alternative means of evaluating these skills.

Faculty perceived some listening skills as more important than others for academic success. These included nine skills in particular that were related primarily to various aspects of lecture content (e.g., identifying major ideas and relationships among them). As might be expected, faculty perceived that nonnative students experience more difficulty than native students with all listening activities, and that nonnative students have disproportionately greater difficulty with some activities, such as following lectures given at different speeds and comprehending or deducing the meaning of important vocabulary. With respect to measuring listening comprehension, some general approaches and specific item types were judged to be more appropriate than others. These included tasks that entail answering questions involving the recall of details as well as those involving inference or deductions.

The results of the survey are used to suggest further research on the construct validity of the Listening Comprehension section of the TOEFL® test.
THE PSYCHOMETRIC CHARACTERISTICS OF THE GRE GENERAL TEST FOR THREE HANDICAPPED GROUPS
Authors: Bennett Randy Elliot , Rock Donald A. , Jirele Thomas
Published: September 2014

This study examined the psychometric characteristics of the Graduate Record Examinations (GRE) General Test for three handicapped groups. Information about test characteristics is central to judging the accuracy and fairness of General Test scores for handicapped students.

Four psychometric characteristics were studied: level of test performance, test completion, test reliability, and unexpected differential item performance. Psychometric comparisons were made between nonhandicapped samples and each of three handicapped groups: visually impaired students taking large‐type, extended‐time administrations; visually impaired students taking timed, regular‐type administrations; and physically handicapped students taking timed, regular‐type administrations.

Results of the study showed the performance of the visually handicapped groups to closely approximate that of nondisabled students. Physically handicapped students, however, performed substantially lower than the comparison group on two of the three General Test scales.

Data on test completion showed evidence of possible disadvantage to the two groups of disabled examinees taking timed administrations. Evidence that handicapped students were somewhat less likely to complete the test was found for both groups on the Analytical sections and for one group on the first Quantitative section. Though these scores may, as a result, underestimate developed scholastic ability, any conclusion on this account must await the findings of further research.

Test reliability was analyzed using both internal consistency and parallel‐forms methods. Neither method revealed any practical differences in measurement precision across groups.

Because of the large number and general unreliability of individual item‐performance contrasts, unexpected differential item performance was examined through a two‐stage procedure. The first stage centered on the performance of item clusters. Items composing clusters showing questionable performance were then individually examined. This two‐stage procedure revealed only two instances–localized to visually impaired students taking the large‐type test–of differential item performance.

In terms of both reliability and item behavior, the psychometric characteristics of the GRE General Test appear comparable for the handicapped and nondisabled groups studied. Though somewhat less comparable, test completion and performance levels also were similar across groups. Further studies of General Test scores–in particular, their factor structure and predictive validity–should provide additional information about their meaning for handicapped students.
THE INTERNAL CONSTRUCT VALIDITY OF THE GRE GENERAL TEST ACROSS HANDICAPPED AND NONHANDICAPPED POPULATIONS
Authors: Rock Donald A. , Bennett Randy Elliot , Jirele Thomas
Published: September 2014

This study investigated the factor structure of the GRE General Test across handicapped and nonhandicapped groups, The handicapped student groups included two groups of examinees taking timed, standard administrations and one taking an extended‐time, large‐type administration. A simple, three‐factor model, consisting of Verbal, Quantitative, and Analytical item types was posed. Using the covariance matrices, this model was tested for invariance with respect to the number and intercorrelation of factors, the pattern of factor loadings, and the equality of scale units. To investigate observed discrepancies in factor structure, a higher‐order factor solution using the correlation matrices was also computed.

The three common‐factor model provided a good fit in the nonhandicapped population and a moderately good fit for visually impaired students taking a standard administration. The least adequate fit was found for the visually impaired group taking the large type exam and for physically impaired students taking a standard administration. While the verbal and quantitative factors fit reasonably well in these two groups, the analytical factor fit less adequately, with the item types composing this factor–analytical reasoning and logical reasoning–behaving more as separate factors. For both groups, Analytical scores appeared to have a different meaning from those for nonhandicapped students.

For visually impaired students taking the large type exam, a lower relationship between the verbal and quantitative factors was noted. This lower relationship indicates, relative to nonhandicapped students, an increased likelihood of achievement growth in one area independent of the other. This finding underscores the importance of interpreting Verbal and Quantitative scores individually rather than as part of a composite.

Findings from this study should be interpreted with caution because of the small sample sizes on which results are based and because the study only provides one component of the evidence required to make summative judgments of test validity. Further evidence from predictive and item validity studies should add to the information base required for drawing policy and procedural implications about the development and the use of the General Test for handicapped examinees.
SOME PROPERTIES OF THE PEARSON CORRELATION MATRIX OF GUTTMAN‐SCALABLE ITEMS
Authors: Zwick Rebecca
Published: September 2014

Although perfectly scalable items rarely occur in practice, Guttman's concept of a scale has proved to be valuable to the development of measurement theory. If the score distribution is uniform and there is an equal number of items at each difficulty level, both the elements and the eigenvalues of the Pearson correlation matrix of dichotomous Guttman‐scalable items can be expressed as simple functions of the number of items. Even when these special conditions do not hold, the values of the correlations can be computed easily by assuming a particular score distribution. These findings are useful in conducting research on the properties of scales.
EFFECTS OF TEST PREPARATION ON THE VALIDITY OF GRE ANALYTICAL SCORES
Authors: Powers Donald E.
Published: September 2014

Test score improvement has been the major concern in nearly all the extant studies of special preparation or “coaching” for tests. Recently, however, logical analyses of the possible outcomes and implications of special test preparation (Anastasi, 1981; Cole, 1982; Messick, 1981) have suggested that the issue of test score effects is but one aspect of the controversy surrounding coaching; the impact of special preparation on test validity is an equally germane consideration. Though the assumption is sometimes made that coaching can serve only to dilute the construct validity and impair the predictive power of a test, some kinds of special preparation may, by reducing irrelevant sources of test difficulty, actually improve both construct validity and predictive validity.

This study examined the relationships of both internal and external criteria to GRE candidates' performance on several analytical ability item types, obtained under several test‐preparation conditions. The purpose was to assess the effects of these various preparations on test reliability and validity. The preparation conditions were those previously shown to be effective, in varying degrees, in improving examinee performance on two of three analytical item types (Powers & Swinton, 1982, 1984). The data for this study were those collected by Powers and Swinton (1982, 1984).

The study results suggest that GRE analytical ability scores may relate more strongly to academic performance after special test preparation than under more standard conditions and that they may relate less to measures of other cognitive abilities (verbal and quantitative scores). No consistent effects were detected on either the internal consistency or the convergent validity of the analytical measure.
GENERALIZATION OF SAT® VALIDITY ACROSS COLLEGES
Authors: Boldt Robert F.
Published: September 2014

This study, which focused on the validity of the SAT‐V and SAT‐M, used data from 99 validity studies that were conducted by the Validity Study Service of the College Board. In addition to test validities based on first‐year college averages, which were calculated using institutional data, validities for each college were also estimated for two other groups—applicants for admission to the colleges, and all SAT takers. These last two estimates were based on range restriction theory.

Substantial validity generalization was found: the assumption that applicant pool validities were all equal, together with sampling variance and the effects of selection, accounted for 36 percent and 34 percent of the variation of the SAT‐V and SAT‐M validities, respectively. The hypothesis of equal validity in pools like those of all SAT takers, plus sampling variance and the effects of selection, accounted for 53 percent and 33 percent of the variation of the SAT‐verbal and SAT‐mathematical validities, respectively. However, significant institutional uniqueness remains, though part of that uniqueness consists of variation in the reliability of first‐year college average.

For these data, substantial validity was the rule. The average validities were quite high, rising to .55 for either SAT‐V or SAT‐M true scores for all SAT takers, and 95 percent of the observed validities were above .13 for SAT‐V and .10 for SAT‐M. Values below these may be owing to accidents of sampling, computing errors, or criterion defects, and it should be noted that 95 percent is a conservative standard. Studies with slightly higher validities may be questioned as well, perhaps repeated, and the criterion examined carefully.

A hypothesis that validities for SAT‐V and SAT‐M might differ across institutions but have the same ratio was also tested. It was thought that departures from this second assumption might lead to the detection of institutional types. However, significant departures from the equal‐ratio hypothesis tested at the 5 percent level occurred for about 5 percent of the institutions, so no detection of institutional types occurred.
GENERALIZED VARIANCE FUNCTIONS FOR A COMPLEX SAMPLE SURVEY
Authors: Johnson Eugene G. , King Benjamin F.
Published: September 2014

For a national survey of reading ability among young adults using a multistage, stratified probability sample, generalized variance functions (GVF) were estimated. That is, an attempt was made to express the estimated variance of a statistic as a function of that statistic and other characteristics of the variable of interest. With GVFs estimated from a development sample of variables, predictions of sampling variance were made for other variables in a confirmation sample and comparisons made with conventional jackknife estimates. Conclusions were drawn about the feasibility of use of GVFs, with emphasis on the margin of additional error that is introduced.
THE RELATIONSHIP BETWEEN MINIMUM COMPETENCY TESTING PROGRAMS AND STUDENTS' READING PROFICIENCY: IMPLICATIONS FROM THE 1983–84 NATIONAL ASSESSMENT OF EDUCATIONAL PROGRESS IN READING AND WRITING
Authors: Winfield Linda F.
Published: September 2014

Exploratory studies presented in this report used multilevel data obtained in the 1983–84 National Assessment of Educational Progress to investigate the relationship between minimum competency testing (MCT) programs and student reading proficiency. A “school effects” paradigm was used in Study 1 to assess the effect of a school‐level MCT program after adjusting for students' age, sex, region of the country, family background, school‐level composition, and socioeconomic status, students' academic behaviors, school‐level remedial program, and instructional dollars per pupil. Within‐race/ethnic group analyses were conducted to investigate whether or not the effect of MCT programs on reading proficiency was similar for each race/ethnic group. The second study examined the relationship between the type of state testing program and reading proficiency for each grade cohort after adjusting for students' age, sex, district and school‐level SES variables, family background, and race. These studies demonstrate the limits and potential of using NAEP data to inform public policy issues.
DOES GUESSING REALLY HELP?
Authors: Angoff William H.
Published: September 2014

This study examined the claim that attempting, or guessing at, more items yields improved formula scores. Two samples of students who had taken a form of the SAT‐verbal consisting of three parallel half‐hour sections were used to form the following scores on each of the three sections: the number of attempts, a guessing index, the formula score, and (indirectly) an approximation to an ability score. Correlations were obtained separately for the two samples between the attempts (and the guessing index) on one section and the formula score on a second section, partialling out ability as measured on the third section. The partial correlations so obtained hovered near zero, suggesting, contrary to conventional wisdom, that attempting more items and guessing are not helpful in yielding higher formula scores, and that, therefore, formula scoring is not disadvantageous to the student who is less willing to guess and attempt an item that he (she) is not sure of.
PATHWAYS TO GRADUATE SCHOOL: AN EMPIRICAL STUDY BASED ON NATIONAL LONGITUDINAL DATA
Authors: Hilton Thomas L. , Schrader William B.
Published: September 2014

In response to widespread concern about the status of graduate schools in the United States, this study was undertaken to investigate:

What proportions of high school seniors enroll in graduate school or professional school.

What proportions of students make certain choices at each of five critical stages in educational development from high school to graduate or professional school.

Whether the proportions making these choices differ for major subgroups of the student population.

How the choices at one stage relate to choices at others.

Whether the proportions for students who reach graduate school differ for those reaching professional school.

Whether the early characteristics of eventual graduate students differ from those of eventual professional school students.

What implications the results of the study might have for the number of students expected to enroll in graduate schools in the late 1980s.

The date analysis relied primarily on data from the National Longitudinal Study of the High School Class of 1972, in which a national probability sample of approximately 22,500 high school seniors was surveyed in 1972 and then resurveyed approximately every two years until 1979. Analysis of data from a survey of 1980 high school seniors provided data on the initial posthigh school choices of a recent cohort.

The data analysis indicated that:

By 1979, 3% of the 1972 high school seniors had enrolled full time in graduate school, and 3% had enrolled full time in professional school.

Students reaching graduate or professional school tended to enroll in more demanding high school academic programs and were noticeably more likely to enroll first in four‐year colleges after high school graduation.

The distribution of males and females in the pathways and their educational attainment were similar, except that appreciably fewer females enrolled in professional schools.

Almost as high a proportion of Black students as of White students enrolled initially in four‐year colleges, but a lower proportion received bachelor's degrees.

Students reaching graduate school tended to show approximately the same pattern of choices as students reaching professional school; the professional school students had somewhat higher test scores and educational aspirations, although the differences were small.

Many uncertainties precluded predictions about their absolute numbers, but it is likely that the proportion of future postbaccalaureate students who are female and the proportions from minority populations will be appreciably higher.
A THEORETICAL FRAMEWORK FOR THE STUDY OF ITEM DIFFICULTY AND DISCRIMINATION
Authors: Scheuneman Janice Dowd , Steinhaus Karin S.
Published: September 2014

Traditionally, test item difficulty is a statistical concept, defined in terms of the performance of examinees rather than in terms of intrinsic properties of the item itself. A clearer understanding of the association between item properties and examinee performance, however, would result in numerous benefits, including better prediction and control of item difficulty in the test development process and enhanced construct validity of the test. As a first step toward the goal of achieving such understanding, a theoretical framework is delineated, drawing on both measurement concepts and concepts drawn from cognitive psychology and personality theory. In this formulation, the difficulty of an item is seen as a function of the demands set by the item tasks and the abilities and attributes which the examinee may find necessary or useful in responding correctly to the item. In addition, interactions of examinee abilities and item characteristics may occur where solutions to an item may be reached by using different strategies or abilities and the difficulty of meeting the item demand using these different approaches is not equivalent. Examples from the measurement and psychological literature provide suggestions of a number of examinee characteristics and item properties which might be expected to affect item difficulty. The formulation is then extended to item discrimination. Finally, the literature on verbal analogies is reviewed within the theoretical framework to suggest sources of variation in the difficulty and discrimination of this item type.