bluuebunny/crossref_metadata_2025 huggingface dataset:
Teaching and the Faculty Role: Enhancing the Commitment to Instruction in American Colleges and Universities
Authors: Fairweather James S. , Rhoads Robert A.
Published: March 2008

This article focuses on the role administrative action, socialization, and self-motivation play in shaping faculty behavior related to the teaching role. Drawing on a national database, the authors introduce a model that examines two teaching-related outcomes: (a) percentage of time spent on teaching and instruction and (b) preferred amount of teaching. The authors discuss policy implications in terms of four areas: early intervention, faculty/institutional fit, work allocation and workload, and rewards.
Where Has the Money Gone? An Analysis of School District Spending in New York
Authors: Lankford Hamilton , Wyckoff James
Published: March 2008

An important, but infrequently discussed, aspect of whether “money matters” concerns how school district expenditures have been allocated. New York state school districts spent $12 billion more on public K–12 education in 1991–1992 than in 1979–1980. School districts increased real expenditures per pupil by 46% over the 1980–92 period. A surprisingly large portion of the additional spending has gone to students designated as disabled, whereas the share of the new money to nondisabled students has substantially decreased. Other findings address the growth in administrative expenditures, district responses to changing enrollments, and increased compensation for teachers.
Examining Values and Beliefs About Teaching Diverse Students: Understanding the Challenges for Teacher Education
Authors: Tatto Maria Teresa
Published: March 2008

This paper presents empirical evidence regarding the capacity of teacher education programs to influence the values and beliefs of those who enroll in them and offers insight into the conditions that may be conducive to such effects. Our study shows that although teacher education faculty and enrollees across the programs studied subscribe to ideals of social justice and fairness in regard to teaching diverse learners, it is less clear how they translate these ideals into their views concerning curriculum design and implementation, assessment of student progress, and classroom and school organization. Our findings indicate that lay culture norms among enrollees are strongly ingrained and that most teacher education, as it is currently structured, is a weak intervention to alter particular views regarding the teaching and management of diverse learners.
Gender Differences Among New Recruits to School Administration: Cautionary Footnotes to an Optimistic Tale
Authors: Riehl Carolyn , Byrd Mark A.
Published: March 2008

In this study, we examine factors associated with the career move from school teaching to building-level administration, using nationally representative data on about 4,800 elementary and secondary public school teachers. Having administrative experience and a degree in administration were the most important predictors of becoming an administrator. Planning to leave teaching improved men’s chances, while family context decreased women’s chances. Overall, socialization factors—having aspirations, qualifications, and experience—were salient for both men and women. Nevertheless, the positive effects of these factors for women did not counteract other factors, including unmeasured ones, and so women’s predicted probability of becoming a school administrator remained far below that for men.
High School Size: Which Works Best and for Whom?
Authors: Lee Valerie E. , Smith Julia B.
Published: March 2008

The study described in this article investigates the relationship between high school size and student learning. We used three waves of data from NELS:88 and hierarchical linear modeling (HLM) methods to examine how students’ achievement growth in two subjects (reading and mathematics) over the high school years is influenced by the size of the high school they attend. Three research questions guided the study: (a) Which size high school is most effective for students’ learning?, (b) In which size high school is learning most equitably distributed?, and (c) Are size effects consistent across high schools defined by their social compositions? Results suggest that the ideal high school, defined in terms of effectiveness (i.e., learning), enrolls between 600 and 900 students. In schools smaller than this, students learn less; those in large high schools (especially over 2,100) learn considerably less. Learning is more equitable in very small schools, with equity defined by the relationship between learning and student socioeconomic status (SES).

An important finding from the study is that the influence of school size on learning is different in schools that enroll students of varying SES and in schools with differing proportions of minorities. Enrollment size has a stronger effect on learning in schools with lower-SES students and also in schools with high concentrations of minority students. Implications for educational policy are discussed.
Remedial Education As Ideological Battleground: Emerging Remedial Education Policies in the Community College
Authors: Shaw Kathleen M.
Published: March 2008

While remedial education has become an increasingly common aspect of all sectors of postsecondary education, recent ideological debates have resulted in state and system-wide policies that increasingly segregate remediation solely within the community college sector. This trend has profound implications for access to educational opportunity for large segments of the population, particularly the poor and minority students who are most often placed in remedial courses. This article first examines the ideological underpinnings of the current debate regarding the purpose and positioning of remedial education. Next, I utilize qualitative data on three urban community colleges to examine the ways in which the interplay between state- and institutional-level ideology and policy is reflected in individual colleges' remediation practices. The data suggest that community colleges respond quite differently to state-level remediation policies and can play an active role in shaping the implementation of these policies.
Students, Schools, and Enrollment in Science and Humanity Courses in Israeli Secondary Education
Authors: Ayalon Hanna , Yogev Abraham
Published: March 2008

This article examines the deteriorating status of the humanities and social sciences versus mathematics and the sciences in the curriculum of Israeli high schools. We examine this tendency by conducting a multi-level analysis of the effect of school and individual characteristics on inequality in curriculum specialization on a sample of academic-track 12th-graders in 1989. The main findings are (a) more able students, males, and members of the privileged Jewish ethnic group in Israel tend to specialize in mathematics and the sciences, and (b) students’ characteristics are the major determinant of course-taking in mathematics and the sciences, whereas school policy is central regarding the humanities and social sciences. The article discusses social implications of the findings.
Performance-Based Assessment and Instructional Change: The Effects of Testing in Maine and Maryland
Authors: Firestone William A. , Mayrowetz David , Fairman Janet
Published: March 2008

To examine how performance-based assessment changed mathematics teaching under conditions of moderate and low stakes, we studied middle school teachers in five districts in Maine and Maryland. Our observations suggest that the effects of state testing on teaching may be overrated by both advocates and opponents of such policies. When combined with moderately high stakes and other conditions, such assessments generate considerable activity focused on the test itself. This activity can promote certain changes, like aligning subjects taught with the test. It appears to be less successful, however, in changing basic instructional strategies.
Comparing High Schools with Respect to Student Performance in University
Authors: Rubin Donald B. , Stroud T. W. F.
Published: March 2008

This report presents data analyses investigating the relationship of high school final average, X, and first year university average, Y, in a Canadian university. The statistical summaries are (1) a matrix of observed “relative grading standards” of each high school in each matriculation year, and (2) a quadratic regression relating Y to X in each year. These summaries suggest that (1) the grading standards for some of the schools are changing consistently in time, and (2) the general relationship between Y and X is becoming more quadratic and less linear in time. The implication is that the high school attended is a more important predictor of university performance for students with poorer high school records than for students with better high school records, especially in recent years.
Variance Stabilizing Transformations and the Power of the F Test
Authors: Budescu David V. , Appelbaum Mark I.
Published: March 2008

The effect of the variance stabilizing transformations on the significance level and power of the F test, applied to Binomial and Poisson variables, was examined by a Monte Carlo study. The results indicate that the significance level is not affected by the transformations and that in most cases the power is not systematically increased by them,
The Standard Error of Equipercentile Equating
Authors: Lord Frederic M.
Published: March 2008

The standard error of an equipercentile equating is derived for four situations. Some numerical results are checked by Monte Carlo methods. Numerical standard errors are computed for two sets of real data. Standard errors of linear and equipercentile equating are compared.
Conditional Correlation Phenomena with Applications to University Admission Strategies
Authors: Akemann Charles A. , Bruckner Andrew M. , Robertson James B. , Simons Stephen , Weiss Max L.
Published: March 2008

This paper considers the situation (as in college admissions) where one is given two attributes, X and Y, which one uses to predict a third attribute, Z, by some function Ẑ of X and Y. However, one only retains values of X, Y, and Z for which Ẑ is large. A thorough discussion, under fairly general conditions on the distributions, is given of how the correlation coefficients of X, Y, and Z are affected by this restriction of the range of values. In the case of the normal distribution, where linear prediction is optimal, the role of suppressor variables is discussed.
Approximating the Probability of Selecting the Best Treatment With A Heteroscedastic Procedure When The First Stage Has Unequal Sample Sizes
Authors: Wilcox Rand R.
Published: March 2008

Consider k normal distributions having means μ1,..., μk and variances σ21,..., σ2 k. Let μ[1]≥...≥ μ[ k] be the means written in ascending order. Dudewicz and Dalai proposed a two-stage procedure for selecting the population having the largest mean μ[ k] where the variances are assumed to be unknown and unequal. This paper considers an approximate but conservative solution for situations where unequal sample sizes are used in the first stage. The paper also considers how to estimate the actual probability of selecting the “best” treatment; that is, the one having mean μ[ k], after a heteroscedastic ANOVA has been performed.
Estimation of Effect Size under Nonrandom Sampling: The Effects of Censoring Studies Yielding Statistically Insignificant Mean Differences
Authors: Hedges Larry V.
Published: March 2008

Quantitative research synthesis usually involves the combination of estimates of the standardized mean difference (effect size) derived from independent research studies. In some cases, effect size estimates are available only if the difference between experimental and control group means is statistically significant. If the quantitative result of a study is observed only when the mean difference is statistically significant, the observed mean difference, variance, and effect size are biased estimators of the corresponding population parameters. The exact distribution of the sample effect size is derived for the case in which only studies yielding statistically significant results may be observed. The maximum likelihood estimator of effect size also is derived under the model in which only significant results are observed. The exact distribution of the maximum likelihood estimator is obtained numerically and is used to study the bias of the maximum likelihood estimator. An empirical sampling study is used to supplement the analytic results.
Empirical Bayes Meta-Analysis
Authors: Raudenbush Stephen W. , Bryk Anthony S.
Published: March 2008

As interest in quantitative research synthesis grows, investigators increasingly seek to use information about study features—study contexts, designs, treatments, and subjects—to account for variation in study outcomes. To facilitate analysis of diverse study findings, a mixed linear model with fixed and random effects is presented and illustrated with data from teacher expectancy experiments. This strategy enables the analyst to (a) estimate the variance of the effect size parameters by means of maximum likelihood; (b) pose a series of linear models to explain the effect parameter variance; (c) use information about study characteristics to derive improved empirical Bayes estimates of individual study effect sizes; and (d) examine the sensitivity of all substantive inferences to likely errors in the estimation of variance components.
A Method for Studying the Homogeneity of Test Items with Respect to Other Relevant Variables
Authors: Muthén Bengt
Published: March 2008

Drawing on recently developed methodology for structural equation modeling with categorical data, this article proposes a new approach for investigating the behavior of a set of dichotomously scored test items in relation to a set of other relevant (observed) variables. This is achieved by considering a linear structural model relating the latent ability variable to a set of observed scores. The approach gives information on hypothesized unidimensionality and homogeneity of items with respect to these other variables. Some examples are given where a set of biology anchor items is related to a set of other related test scores obtained from the examinees.
Multiple Group IRT Modeling: Applications to Item Bias Analysis
Authors: Muthén Bengt , Lehman James
Published: March 2008

This article shows the applicability of new methodology for multiple-group factor analysis of dichotomous variables. Situations are considered where the same set of test items has been administered to more than one group of examinees. The new methodology is contrasted with the IRT approach to item bias analysis. An example is given in which females and males have taken a certain biology test.
A Bayesian Version of Rasch’s Multiplicative Poisson Model for the Number of Errors of an Achievement Test
Authors: Jansen Margo G. H.
Published: March 2008

Apart from the widely known logistic model for binary scored items, Rasch developed several other models for the analysis of achievement test data. The model considered in this paper is the so-called multiplicative Poisson model for misreadings. This model assumes that the number of reading errors that an individual makes when reading a text is approximately Poisson distributed with an intensity parameter λ, which depends on the ratio of two other parameters, one pertaining to the ability of the individual and one to the difficulty of the words in the text. In this paper a Bayesian procedure is developed for the simultaneous estimation of the ability and difficulty parameters. Similar procedures have been applied to the estimation of the parameters of the logistic model. According to several criteria, the Bayesian estimates are better than comparable maximum likelihood estimates. The method is illustrated by an empirical example. Some evidence on the potential usefulness of the method, based on Monte Carlo studies, is given.
Derivations of Observed Score Linear Equating Methods Based on Test Score Models for the Common Item Nonequivalent Populations Design
Authors: Woodruff David
Published: March 2008

Linear equating methods for the common item nonequivalent populations design are derived from explicitly stated test score models. The models are congeneric type models for tests administered in two distinct populations. Though the data collected in the design are incomplete, procedures for estimating all parameters necessary for equating are derived. The equating methods developed are compared with previously developed methods to which they are similar. By developing explicit models for the problem, insight is gained into the assumptions required for its solution.
Effect Size Standard Errors for the Non-Normal Non-Identically Distributed Case
Authors: Thomas Hoben
Published: March 2008

Suppose there are k independent studies and for each study the experimental and control groups have been sampled from independent but essentially arbitrary populations. The problem is to construct a plausible standard error of the effect size mean (effect sizes are standardized experimental-control group mean differences) when given only minimal sample statistic information. Standard errors based on the sample standard error, or bootstrap, will typically be much too large and have very large variance. A normal theory estimator may prove practically useful in more general settings. Asymptotic distribution-free estimators are provided for two cases.
Melvin R. Novick: Contributions to the Theory and Practice of Educational and Psychological Measurement
Authors: Linn Robert L.
Published: March 2008

I was privileged to have the opportunity to work closely with Melvin Novick on a half a dozen different committees during the last 10 years. These interactions always proved to be useful learning experiences for me. I have encountered few individuals with such a keen analytical mind. The depth and scope of Novick’s contributions deserve special treatment; I hope this review will at least serve as a reminder of some of his significant contributions to the theory and practice of educational and psychological measurement. For a full appreciation of these contributions, however, there is no substitute for his original publications.
Type I Error Rates and Power Estimates of Selected Parametric and Nonparametric Tests of Scale
Authors: Olejnik Stephen F. , Algina James
Published: March 2008

Estimated Type I error rates and power are reported for the Brown-Forsythe, O’Brien, Klotz, and Siegel-Tukey procedures. The effect of aligning the data, by using deviations from group means or group medians, is investigated for the latter two tests. Normal and non-normal distributions, equal and unequal sample-size combinations, and equal and unequal means are investigated for a two-group design. No test is robust and most powerful for all distributions, however, using O’Brien’s procedure will avoid the possibility of a liberal test and provide power almost as large as what would be provided by choosing the most powerful test for each distribution type. Using the Brown-Forsythe procedure with heavy-tailed distributions and O’Brien’s procedure for other distributions will increase power modestly and maintain robustness. Using the mean-aligned Klotz test or the unaligned Klotz test with appropriate distributions can increase power, but only at the risk of increased Type I error rates if the tests are not accurately matched to the distribution type.
Estimation for the Rasch Model When Both Ability and Difficulty Parameters Are Random
Authors: Rigdon Steven E. , Tsutakawa Robert K.
Published: March 2008

Estimation of the parameters of the Rasch model, a one-parameter item response model, is considered when both the item parameters and the ability parameters are considered random quantities. It is assumed that the item parameters are drawn from a N(γ, τ2) distribution, and the abilities are drawn from a N(0, σ2) distribution. A variation of the EM algorithm is used to find approximate maximum likelihood estimates of γ, τ, and σ. A second approach assumes that the difficulty parameters are drawn from a uniform distribution over part of the real line. Real and simulated data sets are discussed for illustration.
Does the Correlation Coefficient Really Measure the Degree of Clustering Around a Line?
Authors: Loh Wei-Yin
Published: March 2008

This paper derives a formula for the square of the correlation coefficient r2 in terms of its maximum possible value under rotation of the axes. The value of r2 is minimized at 0 when the principal components of the scatterplot coincide with the axes, and is maximized when the principal components are at ±45° to the axes. An application of the formula to quick visual estimation of r is indicated.
The Shrunken Generalized Distance Estimator of the Actual Error Rate in Discriminant Analysis
Authors: Dorans Neil J.
Published: March 2008

A new estimator of the actual error rate for the two-group discriminant problem is presented. The new estimator is based on the concept of a shrunken generalized distance. This new estimator is compared favorably to two modified distance estimators and an estimator developed by Okamoto.
Repeated Measures Multiple Comparison Procedures: Effects of Violating Multisample Sphericity in Unbalanced Designs
Authors: Keselman H. J. , Keselman Joanne C.
Published: March 2008

Two Tukey multiple comparison procedures as well as a Bonferroni and multivariate approach were compared for their rates of Type I error and any-pairs power when multisample sphericity was not satisfied and the design was unbalanced. Pairwise comparisons of unweighted and weighted repeated measures means were computed. Results indicated that heterogenous covariance matrices in combination with unequal group sizes resulted in substantially inflated rates of Type I error for all MCPs involving comparisons of unweighted means. For tests of weighted means, both the Bonferroni and a multivariate critical value limited the number of Type I errors; however, the Bonferroni procedure provided a more powerful test, particularly when the number of repeated measures treatment levels was large.
Item Parameter Estimation Via Marginal Maximum Likelihood and an EM Algorithm: A Didactic
Authors: Harwell Michael R. , Baker Frank B. , Zwarts Michael
Published: March 2008

The Bock and Aitkin (1981) Marginal Maximum Likelihood/EM approach to item parameter estimation is an alternative to the classical joint maximum likelihood procedure of item response theory. Unfortunately, the complexity of the underlying mathematics and the terse nature of the existing literature has made understanding of the approach difficult. To make the approach accessible to a wider audience, the present didactic paper provides the essential mathematical details of a marginal maximum likelihood/EM solution and shows how it can be used to obtain consistent item parameter estimates. For pedagogical purposes, a short BASIC computer program is used to illustrate the underlying simplicity of the method.
Common Item Equating Using the Loglinear Rasch Model
Authors: Kelderman Henk
Published: March 2008

A method is proposed to equate different sets of items administered to different groups of individuals using the Rasch model. A Rasch equating model is formulated that describes one common Rasch scale in different groups with different but overlapping sets of items. The item parameters can then be estimated simultaneously, avoiding different parameter estimates of common items in different groups. The model can be tested globally to test the hypothesis of one common Rasch scale, and the goodness of link can be tested. The method is based on the quasi-loglinear Rasch model.
Comparison of the Mantel-Haenszel Test With a Randomized and a Jackknife Test for Detecting Biased Items
Authors: Camilli Gregory , Smith Jeffrey K.
Published: March 2008

The Mantel-Haenszel (MH) chi-square test has been shown to have desirable statistical properties in detecting biased items. However, small sample sizes are still of concern, especially when large differences in ability exist between the focal and reference groups. This is because the accuracy and power of the MH test depends on the range of overlap between the focal and reference groups on raw scores, as well as the total sample size at any particular raw score. The MH procedure is compared with (a) a randomization test and (b) a jackknife test, which make weaker distributional assumptions. The MH chi-square significance levels were found to be extremely robust.
Fitting a Serial Correlation Pattern to Repeated Observations
Authors: Edwards Lynne K.
Published: March 2008

When repeated observations are taken at equal time intervals, a simple form of a stationary time series structure may be fitted to the observations. Wallenstein and Fleiss (1979) have shown that the degrees-of-freedom correction factor for time effects has a higher lowerbound for data with a serial correlation pattern (or a simplex pattern) than for data without such a structure. The reanalysis of the example data found in Hearne, Clark, and Hatch (1983) indicated that the correction factor from a patterned matrix could be smaller than the counterpart without fitting a simplex pattern. First, an example from education was used to illustrate the computational steps in obtaining these two correction factors. Second, a simulation study was conducted to determine the conditions under which fitting a simplex pattern would be advantageous over not assuming such a pattern. Fitting a serial correlation pattern did not always produce more powerful tests of time effects than not assuming such a pattern. This was particularly true when correlations were high (ρ > .50). Furthermore, it inflated Type I error rates when the simplex shypothesis was not warranted. Indiscriminately fitting a serial correlation pattern should be discouraged.
Bayesian Joint Estimation of Binomial Proportions
Authors: Viana Marlos A. G.
Published: March 2008

Testing the hypothesis H that k > 1 binomial parameters are equal and jointly estimating these parameters are related problems. A Bayesian argument can simultaneously answer these inference questions: to test the hypothesis H, the posterior probability λ = λ (H | x) of H given the experimental data x can be used; to estimate each binomial parameter, their Bayesian estimates under H and the alternative hypothesis H̄ are combined with weights λ and 1 – λ, respectively.
Small-Sample Accuracy of Approximate Distributions of Functions of Observed Probabilities From t Tests
Authors: Becker Betsy Jane
Published: March 2008

The observed probability p is the social scientist’s primary tool for evaluating the outcomes of statistical hypothesis tests. Functions of p s are used in tests of “combined significance,” meta-analytic summaries based on sample probability values. This study examines the nonnull asymptotic distributions of several functions of one-tailed sample probability values (from t tests). Normal approximations were based on the asymptotic distributions of z(p), the standard normal deviate associated with the one-sided p value; of ln(p), the natural logarithm of the probability value; and of several modifications of ln(p). Two additional approximations, based on variance-stabilizing transformations of ln(p) and z(p), were derived. Approximate cumulative distribution functions (cdfs) were compared to the computed exact cdf of the p associated with the one-sample t test. Approximations to the distribution of z(p) appeared quite accurate even for very small samples, while other approximations were inaccurate unless sample sizes or effect sizes were very large. Approximations based on variance-stabilizing transformations were not much more accurate than those based on ln(p) and z(p). Generalizations of the results are discussed, and implications for use of the approximations conclude the article.
Chapter 1: Overview of the National Assessment of Educational Progress
Authors: Beaton Albert E. , Zwick Rebecca
Published: March 2008

This chapter gives an overview of the design and the statistical and psychometric analysis methods developed for use in the National Assessment of Educational Progress (NAEP). For more than 20 years, NAEP has provided information about the educational achievements of students in American schools. In recent years, NAEP has been gaining in prominence and has also been growing bigger and more complex. In 1990, an assessment of individual states was added to NAEP. Also, it is anticipated that the legislation that prohibits NAEP from reporting district and school results may be removed and that NAEP may return to annual rather than biennial assessments. In addition, future assessments will involve a larger number of innovative items, such as questions for which students must produce their own answers rather than selecting among specified options, tasks in which students are asked to read aloud, and portfolios that consist of classroom work produced over a period of time. NAEP’s never-ending growth and evolution continue to provide new technological challenges to its statisticians and psychometricians.
Power Comparisons of Eight Tests for Sphericity in Repeated Measures Designs
Authors: Cornell John E. , Young Dean M. , Seaman Samuel L. , Kirk Roger E.
Published: March 2008

A Monte Carlo simulation was conducted to investigate the relative power of eight tests for sphericity in randomized block designs. Box’s (1954) epsilon values º = .35, .55, .75, .80, .85, .90, .95, and 1.00 were used to quantify departures from sphericity for rank-1 population covariance matrices of dimension p = 3, 5, 7, and 9. Sample covariance matrices were generated for samples of size n = 10, 15, 20, and 30. The locally best invariant test demonstrated substantial power to detect departures from sphericity—regardless of p— for both small and large samples for rank-1 alternatives. Recommendations are made regarding the use of preliminary tests.
It’s About Time: Using Discrete-Time Survival Analysis to Study Duration and the Timing of Events
Authors: Singer Judith D. , Willett John B.
Published: March 2008

Educational researchers frequently ask whether and, if so, when events occur. Until relatively recently, however, sound statistical methods for answering such questions have not been readily available. In this article, by empirical example and mathematical argument, we demonstrate how the methods of discrete-time survival analysis provide educational statisticians with an ideal framework for studying event occurrence. Using longitudinal data on the career paths of 3,941 special educators as a springboard, we derive maximum likelihood estimators for the parameters of a discrete-time hazard model, and we show how the model can befit using standard logistic regression software. We then distinguish among the several types of main effects and interactions that can be included as predictors in the model, offering data analytic advice for the practitioner. To aid educational statisticians interested in conducting discrete-time survival analysis, we provide illustrative computer code ( SAS, 1989 ) for fitting discrete-time hazard models and for recapturing fitted hazard and survival functions.
Automated Parallel Test Construction Using Classical Test Theory
Authors: Armstrong Ronald D. , Jones Douglas H. , Wang Zhaobo
Published: March 2008

A network-flow model is formulated for constructing parallel tests based on classical test theory using test reliability for the criterion. The model enables practitioners to specify a test difficulty distribution for the values of the item difficulties as well as test composition requirements. Use of the network-flow algorithm ensures high computational efficiency, allowing wide applications of optimal test construction using microcomputers. The results of an empirical study show that the generated tests have acceptably high test reliability.
Reliability of Essay Rating and Score Adjustment
Authors: Longford N. T.
Published: March 2008

A model-based approach to rater reliability for essays read by multiple readers is presented. The approach is motivated by the generalizability theory. Variation of rater severity (between-rater variation) and rater inconsistency (within-rater variation) is considered in the presence of between-examinee variation. An additive variance component model is posited and the method of moments for its estimation described. The models involve no distributional assumptions other than variance homogeneity and independence of certain random variables. Minimum mean squared error estimators of examinees’ true scores and readers’ severities are derived. Model diagnostic procedures are an integral component of the approach. The methods are illustrated on data from standardized educational tests.
On Sample Size Requirements for Johansen’s Test
Authors: Coombs William T. , Algina James
Published: March 2008

Type I error rates for the Johansen test were estimated using simulated data for a variety of conditions. The design of the experiment was a 2 × 2× 2× 3× 9× 3 factorial. The factors were (a) type of distribution, (b) number of dependent variables, (c) number of groups, (d) ratio of the smallest sample size to the number of dependent variables, (e) sample size ratios, and (f) degree of heteroscedasticity. The results indicate that Type I error rates for the Johansen test depend heavily on the number of groups and the ratio of the smallest sample size to the number of dependent variables. Type I error rates depend to a lesser extent on the distribution types used in the study. Based on the results, sample size guidelines are presented.
A Kernel-Smoothed Version of SIBTEST With Applications to Local DIF Inference and Function Estimation
Authors: Douglas Jeffrey A. , Stout William , DiBello Louis V.
Published: March 2008

Smoothed SIBTEST, a nonparametric DIF detection procedure, amalgamates SIBTEST and kernel-smoothed item response function estimation. This procedure assesses DIF as a function of the latent trait θ that the test is designed to measure. Smoothed SIBTEST estimates this Junction with increased efficiency, as compared to SIBTEST, while providing hypothesis tests of local and global DIF. By means of kernel smoothing, smoothed SIBTEST reduces noise in local DIF estimation while retaining SIBTEST’s reduction of group-ability-difference-induced DIF estimation bias via use of regression-corrected estimates of ability as design points in the kernel smoothing. By contrast with most nonparametric procedures, matched examinee score cells are not needed, so sparse cell problems are avoided. The performance of smoothed SIBTEST is studied via simulation and real data analysis.
Improved Type I Error Control and Reduced Estimation Bias for DIF Detection Using SIBTEST
Authors: Jiang Hai , Stout William
Published: March 2008

One emphasis in the development and evaluation of SIBTEST has been the control of Type I error (false flagging of non-differential item functioning [DIF] items) inflation and estimation bias. SIBTEST has performed well in comparative simulation studies of Type I error and estimation bias relative to other procedures such as the Mantel-Haenszel and Logistic Regression. Nevertheless it has for a minority of cases that might occur in applications displayed sizable Type I error inflation and estimation bias.

A vital part of SIBTEST is the regression correction, which adjusts for the Type I error-inflating and estimation-biasing influence of group target ability differences by using the linear regression of true on observed matching subtest scores from Classical Test Theory. In this paper, we propose a new regression correction, using essentially a two-segment piecewise linear regression of the true on observed matching subtest scores. A realistic simulation study of the new approach shows that when there is a clear group ability distributional difference, the new approach displays improved SIBTEST Type I error performance; when there is no group ability distributional difference, its Type I error rate is comparable to the current SIBTEST. We have also conducted a power study which indicates that the new approach has on average similar power as the current SIBTEST. We concluded that the new version of SIBTEST, although not perfectly robust, seems appropriately robust against sizable Type I error inflation, while retaining other desirable features of the current version.
Preventive effect of ritodrine hydrochloride and/or urinary trypsin inhibitor against lipopolysaccharide‐induced preterm delivery in mice
Authors: Kaga Nobuhiko , Katsuki Yukio , Kajikawa Satoshi , Shibutani Yasunori
Published: March 2008

Background. The purpose of this study was to confirm the preventive effect of ritodrine hydrochloride (ritodrine) alone or ritodrine plus urinary trypsin inhibitor (UTI) in a mouse model of preterm delivery.

Methods. On day 17 of pregnancy, female C3H/HeN mice impregnated by male B6D2F1 mice were given two intraperitoneal injections of lipopolysaccharide (LPS) (50 μg/kg) at a 3‐hour interval, which induced a 100% incidence of preterm delivery within 25 hours of the second dose. Ritodrine (1, 3, or 10 mg/kg, po), UTI (25 × 104units/kg, ip), ritodrine (3 mg/kg, po) plus UTI (25×104units/kg, ip), distilled water (10 ml/kg, po), or distilled water (10 mg/kg, po) plus saline solution (10 ml/kg, ip) were administered to the pregnant animals 10 times at 1‐hour intervals from 8:00 AM to 5:00 PM on day 18 of pregnancy. In addition, the preventive effect of ritodrine, UTI, or ritodrine plus UTI was examined on LPS‐induced contraction of uterine muscle strips isolated from pregnant mice on day 17 of gestation. Results. The incidence of preterm delivery decreased significantly in a dose‐dependent fashion with ritodrine treatment, and there was a significant and synergistic decrease after combined treatment with ritodrine plus UTI. The in vitro uterine contraction induced by LPS was significantly suppressed by both ritodrine and UTI.

Conclusions. Combination therapy with ritodrine plus UTI may be helpful for preventing preterm delivery in humans without the cardiovascular side effects that often accompany treatment with ritodrine alone.
A study on prophylactic antibiotics in cesarean sections ‐ is it worthwhile?
Authors: Yip Shing‐Kai , Lau Tze‐Kin , Rogers Michael Scott
Published: March 2008

Background. To study the effect of single‐dose prophylactic Augmentin™ on patients under‐going cesarean section.

Methods and material. Three hundred and twenty women undergoing cesarean section were randomized into two groups in a prospective, double‐blind, placebo‐controlled study. One hundred and sixty women were allocated to receive a single‐dose of 1.2 g Augmentin™ at induction of anesthesia and 160 were allocated to a control group who received placebo. The following post‐cesarean outcome parameters were compared between the two groups: duration of hospital stay, febrile morbidity, urine microscopy, bacteriuria, endometritis, and wound infection.

Results. There was no significant difference between the two groups with respect to the duration of post‐operative hospital stay or the incidence of febrile morbidity, endometritis, and wound infection. However, the study group had fewer post‐operative abnormalities in urine microscopy (p<0.05) and bacteriuria (p<O.Ol). The bacterial flora were also different between the two groups.

Conclusion. Single‐dose prophylactic AugmentinTM did not produce any clinically significant improvement in the post‐operative course of patients undergoing cesarean section. If proper surgical techniques are followed in association with closed rectus sheath drainage, it is unlikely that any trial of antibiotics will be able to demonstrate any clinically significant outcome.
Clinical and urodynamic characteristics of women with recurrent urinary incontinence after Burch colposuspension
Authors: KjøLhede Preben , RydéN Gunnar
Published: March 2008

Objective. The purpose of this study was to determine the clinical and urodynamic characteristics of women with recurrent urinary incontinence after Burch colposuspension.

Methods. The participants were assessed with medical history, uro‐gynecological examination and urodynamic investigation consisting of pad‐test, urethrocystoscopy, cough provocation test, cystometry, urethra profilometry and fiowmetry.

Results. Women with RUI demonstrated significantly increased incidences of recurrent lower urinary tract infection (24% vs. 8%), lumbago and sciatica (66% vs. 38%), rectocele (80% vs. 21%), and enterocele (24%> vs. 0%) compared to women with primary stress urinary incontinence. Hypermobility of the bladder neck and urethra and palpable contraction of the levator ani muscles was observed significantly more often among the women with primary stress incontinence (90% vs. 42% and 83% vs. 56%>, respectively). The leakage in women with RUI was significantly less pronounced than among women with primary stress incontinence. Detrusor instability was found significantly more often in women with RUI (47.5% vs. 23%). Low urethra pressure was found in five women with RUI.

Conclusion. Women with RUI after Burch colposuspension seem to have a more pronounced pelvic floor weakness than women with primary stress urinary incontinence, whereas the urinary leakage is less pronounced. Recurrent lower urinary tract infection, lumbago and sciatica as well as detrusor instability are commonly observed whereas low urethral closure pressure is rare in women with RUI after Burch colposuspension.
Epididymal and testicular sperm for intracytoplasmic sperm injection in the treatment of obstructive azoospermia
Authors: Rosenlund Björn , Sjöblom Peter , Dimitrakopoulos Anna , Hillensjö Torbjörn
Published: March 2008

Background. The possibility of treating male infertility because of obstructive azoospermia has been poor, but intracytoplasmic sperm injection (1CSI) has given this type of infertility sufferer a new option.

Material and methods. In this study 13 couples with obstructive azoospermia were treated in a total of 19 stimulated IVF cycles. The men were between 27 and 45 (mean 33) years of age. Their partners, 24–39 (mean 31) years of age were treated according to routine IVF procedures, i.e. down regulation with buserelin followed by hyperstimulation with urofollitropin. Fertilization was obtained by ICSI. Two embryos were transferred on day two after the ovum pick up. Sperm were retrieved through microsurgical epididymal aspiration (MESA) in four cycles, percutaneous epididymal sperm aspiration (PESA) in three cycles and through testicular sperm extraction (TESE) in 12 cycles.

Results. The overall fertilization rate was 68%, with a cleavage rate of 82%. The fertilization rate was equal (68%) with epididymal and testicular sperm and the cleavage rate was 87% and 80%, respectively. Embryos were obtained for embryo transfer (ET) in all cases and five pregnancies (one twin pregnancy) were established (26% per ET), three using epididmal sperm and two using testicular sperm.

Conclusion. Infertility due to obstructive azoospermia can successfully be treated with epididymal sperm and ICSI. When epididymal sperm cannot be found sperm extracted from a testicular biopsy can be used. PESA and TESE are quicker and easier alternatives to MESA and can be performed on an outpatient basis with local anesthesia.
High risk HPV persists after treatment of genital papillomavirus infection but not after treatment of cervical intraepithelial neoplasia
Authors: Strand Anders , Wilander Eric , Zehbe Ingeborg , Rylander Eva
Published: March 2008

Background. Knowledge about the natural course of HPV infection is still limited. In this study we investigated the presence of HPV DNA after treatment and clinical clearance of infection.

Methods. Eighty‐two women treated for genital HPV infection at the STD clinic in Uppsala were consecutively selected for the study. After treatment with podophyllotoxin, and in some cases laser vaporization, a cell sample was taken at the follow‐up visit 6–12 months after clinical clearance of the lesions as evaluated by colposcopy. Samples were analysed with PCR to detect HPV DNA. As a reference group, women treated for cervical intraepithelial neoplasia (ON) with laser surgery, either with cone biopsy or vaporization, were followed‐up after 6 months for the presence of HPV DNA.

Results. Six to 12 months after clinical clearance of HPV infection, 39 (48%) of the women showed detectable HPV DNA in cell samples from the cervix. Of these, 26 (67%) were found to harbor high risk HPV. six (15%) low risk, and seven (18%) either had more than one HPV type or HPV that could not be classified. All but three of the women treated for ON (90%) were negative for HPV DNA.

Conclusion. After clinical clearance of genital HPV infection half of the women had detectable HPV DNA. This does not necessarily imply that transmission to a new partner may occur, but indicates this possibility. Only 10% of the ON treated women harbored HPV DNA in the cell samples in spite of showing high risk HPV infection before treatment.
Morphological integration and natural selection in the postcranium of wild verreaux's sifaka (Propithecus verreauxi verreauxi)
Authors: Lawler Richard R.
Published: March 2008

Morphological integration manifests as strong phenotypic covariation among interacting traits. In this study, a graph‐theory approach is used to analyze patterns of morphological integration in a wild population of Verreaux's sifaka (Propithecus verreauxi verreauxi). The motivation for this study is to determine the relative roles of development versus function in shaping patterns of morphological integration in the sifaka postcranium. A developmental and a functional hypothesis of integration are compared with the observed pattern of integration and the fit of these hypotheses is assessed using information theoretic statistics. Correlational selection is also estimated on limb elements. Information theoretic statistics indicate that the developmental hypothesis fits the observed pattern of integration slightly better than the functional hypothesis. Only two pairs of traits experience correlational selection but neither of the traits within each pair are morphologically integrated. The observed pattern of integration contains several trait–trait associations that are specified by both the functional and developmental hypotheses. These results likely reflect the nested covariation structure in which a novel locomotor mode, vertical clinging and leaping, is derived from a primitive quadrupedal morphotype. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
Brief communication: New evidence of tuberculosis from prehistoric Korea—Population movement and early evidence of tuberculosis in far East Asia
Authors: Suzuki Takao , Fujita Hisashi , Choi Jong Gyu
Published: March 2008

Tuberculosis has been recognized in Japan and Korea for more than 500 years in historical medical documents. However, the origin and early existence of tuberculosis is poorly understood in these regions. Very recently, skeletal evidence for tuberculosis from the Bronze Age (or Aneolithic) period was reported from Japan and Korea. This article describes a possible case of spinal tuberculosis from an archeological site in Korea, which was dated to the first century BC. This date corresponds to the Aneolithic (Yayoi) period in Japan. Skeletal evidence for tuberculosis during the Bronze Age period found in both Korea and Japan are, therefore, discussed as evidence of the earliest tuberculosis outbreaks in East Asia and as biological indicators of population movement between Korea and Japan during this period. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.