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The Hold Me Tight (HMT) program is a new approach to relationship education based on Emotionally-Focused Therapy (Johnson, 2004), an evidence-based approach to couple therapy. In this exploratory longitudinal research, we examined individual growth in relationship satisfaction and trust for partners in 95 couples in 16 HMT groups across four occasions of measurement: Baseline, Pre-Program, Post-Program and at either 3- or 6-month Follow-Up. We found that relationship satisfaction and trust increased during program participation, and declined during follow-up. We believe our findings provide support for the short-term effectiveness of the HMT program, and suggest a longer period of program delivery may result in improved retention of gains. Finally, we present recommendations for improving the design of future longitudinal research in relationship education. [ABSTRACT FROM AUTHOR]

Using data from the National Longitudinal Survey of Youth for the years 1979-91, the authors investigate how school dropouts' acquisition of a General Educational Development certificate (GED) affected the probability that they would obtain training, post-secondary education, or military service. The authors use the longitudinal data to estimate prototypical training and education profiles. They find that the probability that a dropout participated in post-secondary education or non company training was greater after GED receipt than before for both men and women. Still, less than half of GED recipients obtained post-secondary education or training by age 26. [ABSTRACT FROM AUTHOR]

Despite consensus that school absenteeism has negative consequences for children's life outcomes, until recently, little was known about the prevalence of absenteeism or its potential to moderate the impacts of school-based interventions. This study provides evidence from a randomized experiment of a preschool intervention involving 1,876 children in 64 schools in Chile that chronic absenteeism develops in preschool and is predicted by multiple risk factors for poor academic achievement. We find moreover that individual children's likelihood of absenteeism moderated the intervention's impact on children's language and literacy outcomes such that there were positive impacts of the intervention only for children with the lowest likelihood of absenteeism. Experimental evaluations of school-based interventions that do not take absenteeism into account may thus mask heterogeneous effects. In the context of policy pushes to expand early education and preschool access in the United States and globally, these moderation analyses may prove essential for appropriately interpreting the results of experimental studies of school-based interventions. [ABSTRACT FROM PUBLISHER]

Students receive abundant information about their educational performance, but how this information affects future educational-investment decisions is not well understood. Increasingly, results from state-mandated standardized tests are an important source of information. Students receive a score and a label that summarizes their performance on these tests. Using a regression-discontinuity design, we find persistent effects of earning a more positive label on the collegegoing decisions of urban, low-income students. These findings are important not only for understanding students' educational-investment decisions and the consequences of state testing practices but alsofor researchers using the regression-discontinuity design. [ABSTRACT FROM AUTHOR]

In February 2005, Illinois became the first U.S. state to grant home-based child care providers (HBCPs) the right to form a labor union in order to bargain collectively with the state government. This policy inspired similar efforts across the country and represents a potentially important direction for child care policy. To date, the implications of labor unions for the cost, type, and availability of subsidized child care have not been evaluated empirically. In this study, we examine the impact of granting Illinois HBCPs the right to form a labor union on (a) the type of child care (licensed vs. license-exempt/home-based vs. center-based) used by subsidy-receiving Illinois infants and toddlers; (b) the per-child cost of subsidized child care for infants and toddlers; and (c) the percentage of Illinois infants and toddlers who use child care subsidies. To conduct these analyses, we combine data from the Current Population Survey with Child Care and Development Fund administrative records on U.S. infants and toddlers whose families received child care subsidies during the period from 2002 to 2008. We use both a traditional difference-in-differences as well as a comparative case study with a 'synthetic' control group approach. The synthetic control group approach improves on traditional comparative case studies by providing a transparent, empirical approach for constructing the counterfactual, documenting comparison units' contribution to the synthetically created control group and detailing the degree to which the synthetic control group is, or is not, similar to the treated unit on preintervention measures of the outcome as well as on other selected characteristics. We find that subsidy-receiving Illinois infants and toddlers spent an average of between 6.4 and 7 percentage points more hours in licensed care settings, as compared to license-exempt settings, in the three years following child care unionization. We also find that between 0.7 and 1.1 percentage points fewer Illinois infants and toddlers used child care subsidies following unionization. [ABSTRACT FROM AUTHOR]

This article explores the role of caregivers in the reintegration of former child soldiers from Sierra Leone. Using data on 282 youth and their respective caregivers, our aim is to focus on the caregiver–child relationship after reintegration. We investigate the extent to which caregivers know about child soldiers’ experiences of direct and indirect violence, as well as involvement in war activities. We further examine variables that might shape the degree of caregiver knowledge of child's war experiences. Finally, we examine if caregiver knowledge of war experiences is associated with child's psychosocial outcomes. Findings highlight the importance of developing thoughtful programs that consider the needs of the child in the context of the family and caregivers with whom he or she is reunified. [ABSTRACT FROM AUTHOR]

Background: Beginning in adolescence, females are at significantly higher risk for depression than males. Despite substantial efforts, gaps remain in our understanding of this disparity. This study tested whether gender differences in adolescent-onset depression arise because of female's greater exposure or sensitivity to violence.Methods: Data came from 5,692 participants in the National Comorbidity Survey Replication. Trained interviewers collected data about major depression and participants' exposure to four types of interpersonal violence (physical abuse, sexual assault, rape, and witnessing violence) using a modified version of the Composite International Diagnostic Interview. We used discrete time survival analysis to investigate gender differences in the risk of adolescent onset depression.Results: Of the entire sample, 5.7% met DSM-IV criteria for depression by age 18; 5.8% of the sample reported being physically abused, 11.7% sexually assaulted, 8.5% raped, and 13.2% witnessed violence by age 18. Females had 1.51 times higher odds of depression by age 18 than males. Exposure to all types of violence was associated with an increased odds of depression in both the past year and the years following exposure. Adjusting for exposure to violence partially attenuated the association between gender and depression, especially for sexual assault (odds ratio [OR] attenuated = 1.28; 15.23%) and rape (OR attenuated = 1.32; 12.59%). There was no evidence that females were more vulnerable to the effects of violence than males.Discussion: Gender differences in depression are partly explained by females' higher likelihood of experiencing interpersonal violence. Reducing exposure to sexual assault and rape could therefore mitigate gender differences in depression. [ABSTRACT FROM AUTHOR]

Background Beginning in adolescence, females are at significantly higher risk for depression than males. Despite substantial efforts, gaps remain in our understanding of this disparity. This study tested whether gender differences in adolescent-onset depression arise because of female's greater exposure or sensitivity to violence. Methods Data came from 5,692 participants in the National Comorbidity Survey Replication. Trained interviewers collected data about major depression and participants' exposure to four types of interpersonal violence (physical abuse, sexual assault, rape, and witnessing violence) using a modified version of the Composite International Diagnostic Interview. We used discrete time survival analysis to investigate gender differences in the risk of adolescent onset depression. Results Of the entire sample, 5.7% met DSM- IV criteria for depression by age 18; 5.8% of the sample reported being physically abused, 11.7% sexually assaulted, 8.5% raped, and 13.2% witnessed violence by age 18 . Females had 1.51 times higher odds of depression by age 18 than males. Exposure to all types of violence was associated with an increased odds of depression in both the past year and the years following exposure. Adjusting for exposure to violence partially attenuated the association between gender and depression, especially for sexual assault (odds ratio [ OR] attenuated = 1.28; 15.23%) and rape ( OR attenuated = 1.32; 12.59%). There was no evidence that females were more vulnerable to the effects of violence than males. Discussion Gender differences in depression are partly explained by females' higher likelihood of experiencing interpersonal violence. Reducing exposure to sexual assault and rape could therefore mitigate gender differences in depression. [ABSTRACT FROM AUTHOR]

To document wiki usage in U.S. K–12 settings, this study examined a representative sample drawn from a population of nearly 180,000 wikis. The authors measured the opportunities wikis provide for students to develop 21st-century skills such as expert thinking, complex communication, and new media literacy. The authors found four types of wiki usage: (a) trial wikis and teacher resource-sharing sites (40%), (b) teacher content-delivery sites (34%), (c) individual student assignments and portfolios (25%), and (d) collaborative student presentations and workspaces (1%). Wikis created in schools serving low-income students have fewer opportunities for 21st-century skill development and shorter lifetimes than wikis from schools serving affluent students. This study illustrates the exciting potential that Web 2.0 data warehouses offer for educational research. [ABSTRACT FROM PUBLISHER]

This study capitalizes on a natural experiment that occurred in California between 2000 and 2002. In those years, the state offered a competitively allocated $20,000 incentive called the Governor's Teaching Fellowship (GTF) aimed at attracting academically talented, novice teachers to low‐performing schools and retaining them in those schools for at least four years. Taking advantage of data on the career histories of 27,106 individuals who pursued California teaching licenses between 1998 and 2003, we use an instrumental variable strategy to estimate the unbiased impact of the GTF on the decisions of recipients to begin working in low‐performing schools within 2 years after licensure program enrollment. We estimate that GTF recipients would have been less likely to teach in low‐performing schools than observably similar counterparts had the GTF not existed, but that acquiring a GTF increased their probability of doing so by 28 percentage points. Examining retention patterns, we find that 75 percent of both GTF recipients and nonrecipients who began working in low‐performing schools remained in such schools for at least four years. © 2010 by the Association for Public Policy Analysis and Management. [ABSTRACT FROM AUTHOR]

In specifying a minimum passing score on examinations that students must pass to obtain a high school diploma, states divide a continuous performance measure into dichotomous categories. Thus, students with scores near the cutoff either pass or fail despite having essentially equal skills. The authors evaluate the causal effects of barely passing or failing a high school exit examination on the probability of graduation using a regression discontinuity design. For most Massachusetts students, barely failing their first 10th grade mathematics or English language arts (ELA) examination does not affect their probability of graduating. However, low-income urban students who just fail the mathematics examination have an 8 percentage point lower graduation rate than observationally similar students who just pass. There is no analogous impact from just passing or failing the ELA exit examination. For these urban, low-income students, barely failing the mathematics test does not affect the likelihood of on-time grade promotion, but it does cause students to be 4 percentage points more likely to drop out of school in the year following the test. Low-income urban students are just as likely to retake the test as equally skilled suburban students, but they have less success on retest. [ABSTRACT FROM AUTHOR]

Personality disorders (PDs) have been thought historically to be enduring, inflexible, and set in psychological stone relatively firmly; however, empirical findings from recent prospective multiwave longitudinal studies establish otherwise. Nearly all modern longitudinal studies of personality disorder have documented considerable change in PDs over time, suggesting considerable flexibility and plasticity in this realm of psychopathology. The factors and mechanisms of change in the PDs remain essentially opaque, and this area of PD research is just beginning to be probed using candidate predictors of change, such as personality systems. In this report, we investigate whether change in temperament dimensions (emotionality, activity, and sociability) predicts change in schizoid personality disorder. We present a latent growth framework for addressing this question and provide an illustration of the approach using data from the Longitudinal Study of Personality Disorders. Schizoid personality disorder was assessed using two different methodologies (structured psychiatric interview and self-report) and temperament was assessed using a well-known psychometric measure of temperament. All constructs were measured at three time points over a 4-year time period. To analyze these panel data, we fitted a covariance structure model that hypothesized simultaneous relationships between initial levels and rates of change in temperament and initial levels and rates of change in schizoid personality disorder. We found that rates of change in the core temperament dimensions studied do not predict rates of change in schizoid personality over time. We discuss the methodological advantages of the latent growth approach and the substantive meaning of the findings for change in schizoid personality disorder. [ABSTRACT FROM AUTHOR]

The purpose of this research is to explore the dynamics of cortisol regulation in the context of center-based child care by examining the impact of social context (large classroom vs. small group) and relationship quality with caregivers (conflict with mothers and teachers). We extend the research on children's physiologic stress system functioning in center-based child care by focusing on morning cortisol levels among young children living in poverty. While in high-quality center-based child care, children's cortisol levels decreased over the course of the morning—a result that contrasts with findings in previous research with middle-class children, for whom cortisol typically increased over the course of the day while attending center-based child care. Cortisol levels were further reduced when children were moved from a large classroom environment to a small group context. Relationship conflict with mothers and teachers moderated these effects. Children who had high conflict with their mother exhibited cortisol levels that remained higher (decreased less) over the course of the morning, and children who had high conflict with their teacher exhibited cortisol levels that remained higher (decreased less) in response to the small group context. These results indicate that high-quality child care has the potential to support reduced stress among children living in poverty, at least as indicated by adrenocortical activity. [ABSTRACT FROM AUTHOR]

This article exploits highly detailed data on teacher absences from a large urban school district in the northern United States to shed light on the determinants and effects of teacher absences. The topic is important because both school and district policies can influence teachers' propensity to be absent. The authors estimate the impact of teacher absences on academic achievement of students matched to elementary school teachers. Models include fixed effects for teachers to control statistically for potential correlation between time-invariant levels of teachers' skill and effort and their rates of absence. The authors estimate 10 additional days of teacher absence reduce mathematics achievement of-fourth-grade students by 3.2% of a standard deviation. They employ an additional instrumental variables strategy to bolster the case for a causal interpretation of results. Instrumental variables results indicate the impact of unexpected teacher absences on student achievement is larger than the impact of anticipated absences. [ABSTRACT FROM AUTHOR]

Copyright of Revista Internacional del Trabajo is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revue Internationale du Travail is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article studies the impact of teacher absences on education. Using data spanning three academic years about 285 teachers and 8,631 predominantly economically disadvantaged students from a United States urban school district, it tests assumptions that a substantial portion of teachers' absences is discretionary and that these absences reduce productivity -- students' mathematics scores. Since absent teachers are typically replaced by less qualified substitutes, instructional intensity and consistency may decline: ten days of teacher absence reduce students' achievement score by about 3.3 per cent of a standard deviation -- enough to lower some students' designation in the state proficiency system and, thus, their motivation to succeed. [ABSTRACT FROM AUTHOR]

A study of two long-lived Florida anvils showed that reflectivity >20 dBZ increased in area, thickness, and sometimes magnitude at the midlevel well downstream of the convective cores. In these same regions electric fields maintained strengths >10 kV m-1 for many tens of minutes and became quite uniform over tens of kilometers. Millimetric aggregates persisted at 9–10 km for extended times and distances. Aggregation of ice particles enhanced by the strong electric fields might have contributed to reflectivity growth in the early anvil, but is unlikely to explain observations farther out in the anvil. The enhanced reflectivity and existence of small, medium, and large ice particles far out into the anvil suggest that an updraft was acting, perhaps in weak convective cells formed by instability generated from the evaporation and melting of falling ice particles. It is concluded that charge separation must have occurred in these anvils, perhaps at the melting level but also at higher altitudes, in order to maintain fields >10 kV m-1 at 9–10 km for extended periods of time over large distances. The authors speculate that charge separation occurred as a result of ice–ice particle collisions (without supercooled water being present) via either a noninductive or perhaps even an inductive mechanism, given the observed broad ice particle spectra, the strong preexisting electric fields, and the many tens of minutes available for particle interactions. The observations, particularly in the early anvil, show that the charge structure in these anvils was quite complex. [ABSTRACT FROM AUTHOR]

The article examines the research conducted by Ronald G. Fryer and Steven D. Levitt, focusing on differences by grade in the black-white test score gap in reading and mathematics, based on analyses of data on the Early Childhood Longitudinal Study (ECLS-K) in the U.S. The types of school quality indicators used are discussed. A comparison between the data sets of ECLS-K and the National Institute of Child Health and Human Development (NICHD) is also presented.

The article discusses the educational strategy of subsidizing private schools in expanding school enrollment. This strategy was applied by the city of Bogotá, Colombia, where the city benefited in meeting its commitment to universal access to primary schooling. The author then provides a brief summary of Bogotá's recent strategy, as well as discusses previous research on the effects of class size, peer group composition, and teacher characteristics, particularly in Latin America, with a special focus on the studies that have used the most credible research designs.

The relatively poor average performance of German students on the recent PISA international evaluations of 15- and 16-year-olds' literary skills (2000) and mathematical skills (2003) and the wide variation in performance, with low-income students scoring particularly poorly, have led to calls for reforms of the German educational system. Understanding why students in some classrooms learn more than do those in other classrooms is an important first step in considering alternative reform strategies. Possible explanations include differences in teacher quality, class sizes and peer groups, and also differences among the types of secondary schools that parents select for their children. This paper illustrates a set of techniques that are useful in examining the roles these factors play in predicting why, net of family background and prior achievement, the average achievement of children in some classrooms is much higher than that of children in other classrooms. We illustrate the use of these techniques with a dataset from Bogotá, Colombia, that has two attractive properties. First, some teachers teach multiple classes of students. Second, students are enrolled in schools in two sectors (public and private). Application of the techniques described in this paper could shed light on the reasons why the average academic achievement of German students attending some schools is much higher than that of German students attending other schools. [ABSTRACT FROM AUTHOR]

Background The long-term stability of personality pathology remains an open question. Its resolution will come from prospective, multiwave longitudinal studies using blinded assessments of personality disorders (PD). Informative analysis of multiwave data requires the application of statistical procedures, such as individual growth curve modeling, that can detect and describe individual change appropriately over time. The Longitudinal Study of Personality Disorders, which meets contemporary methodological design criteria, provides the data for this investigation of PD stability and change from an individual growth curve perspective. Methods Two hundred fifty subjects were examined for PD features at 3 different time points using the International Personality Disorders Examination during a 4-year study. Stability and change in PD features over time were examined using individual growth modeling. Results Fitting of unconditional growth models indicated that statistically significant variation in PD features existed across time in the elevation and rate of change of the individual PD growth trajectories. Fitting of additional conditional growth models, in which the individual elevation and rate-of-change growth parameters were predicted by subjects’ study group membership (no PD vs possible PD), sex, and age at entry into the study, showed that study group membership predicted the elevation and rate of change of the individual growth curves. Comorbid Axis I psychopathology and treatment during the study period were related to elevations of the individual growth trajectories, but not to rates of change. Conclusions From the perspective of individual growth curve analysis, PD features show considerable variability across individuals over time. This fine-grained analysis of individual growth trajectories provides compelling evidence of change in PD features over time and does not support the assumption that PD features are traitlike, enduring, and stable over time. [ABSTRACT FROM AUTHOR]

This paper describes part of a project called Modeling Across the Curriculum which is a large-scale research study in 15 schools across the United States. The specific data presented and discussed here in this paper is based on BioLogica, a hypermodel, interactive environment for learning genetics, which was implemented in multiple classes in eight high schools. BioLogica activities, data logging, and assessments were refined across this series of implementations. All students took a genetics content knowledge pre- and posttests. Traces of students' actions and responses to computer-based tasks were electronically collected (via a “log file” function) and systematically analyzed. An intensive 3-day field test involving 24 middle school students served to refine methods and create narrative profiles of students' learning experiences, outcomes, and interactions with BioLogica. We report on one high school implementation and the field test as self-contained studies to document the changes and the outcomes at different phases of development. A discussion of design changes concludes this paper. [ABSTRACT FROM AUTHOR]

Although controversy has always surrounded the measurement of change, it is now known that change can indeed be measured well if a longitudinal perspective is adopted. A sample of individuals must be followed over time and measured repeatedly at sensibly spaced intervals, and an explicit multilevel model for change must be postulated during data analysis. The latter contains two submodels: (a) an individual growth model (Level 1) and (b) a model for systematic interindividual differences in change (Level 2). Recently, methodologists have shown how the multilevel model for change can be mapped onto the general covariance structure model (as implemented in LISREL, say), thereby empowering the use of covariance structure analysis in the measurement of change—a strategy now known as latent growth modeling. Although the statistical model is identical under both approaches, and parameter estimates are generally very close, latent growth modeling offers advantages. It permits the modeling of change simultaneously in several domains, the modeling of change in a construct, the modeling of change as part of a network of relations, and the testing of explicit hypotheses about error covariance structure. In this article, I use longitudinal data on the early reading scores of 1740 children from the Early Childhood Longitudinal Study (National Center for Education Statistics, 2002) to introduce latent growth modeling. [ABSTRACT FROM AUTHOR]

Investigates four educational opportunities pursued by four young women who drop out of high school in the United States. Mechanisms through which educational investments may affect earnings; Brief review of relevant research on the subject; Ways in which women who engage in educational activities differ from those who do not; Effects of education and training on earnings; Effects of different preexisting characteristics on earnings.

Does the labor market reward cognitive skill differences among those with the fewest educational attainment--high school dropouts? This paper explores this question using a data set that provides information on the universe of dropouts who last attempted the GED exams in Florida and New York in 1989 and 1990. This sample reduces variation in unmeasured variables such as motivation that are correlated with cognitive skills. The authors examine the returns to basic cognitive skills as measured by GED test scores. The results indicate substantial earnings returns to cognitive skills for all groups except white male dropouts. [ABSTRACT FROM AUTHOR]

Presents information on a study which discussed characteristics of numerous calibrated wide-band recordings of natural first and subsequent return strokes in cloud-to-ground lightning conditions. Methodology of the study; Results and discussion on the study.

Assesses the importance of teenagers' cognitive skills in predicting subsequent labor market success. Importance and effect of cognitive skills on subsequent earnings; Benefits of college in translating cognitive skills into earnings advantages; Comparison of earnings of students who graduate with strong cognitive skills and those who leave high school.

This paper tests the labor market signaling hypothesis for the General Educational Development (GED) equivalency credential. Using a unique data set containing GED test scores and Social Security Administration (SSA) earnings data, we exploit variation in GED status generated by differential state GED passing standards to identify the signaling value of the GED, net of human capital effects. Our results indicate that the GED signal increases the earnings of young white dropouts by 10 to 19 percent. We find no statistically significant effects for minority dropouts. [ABSTRACT FROM AUTHOR]

Abstract--This paper examines the value of the GED credential and the conventional high school diploma in explaining the earnings of 27-year-old males in the early 1990s. The data base is the High School and Beyond sophomore cohort. We replicate the basic findings of prior studies that implicitly assume the labor market value of the GED credential does not depend on the skills with which dropouts left school. We show that these average effects mask a more complicated pattern. Obtaining a GED is associated with higher earnings at age 27 for those male dropouts who had very weak cognitive skills as tenth graders, but not for those who had stronger cognitive skills as tenth graders. [ABSTRACT FROM AUTHOR]

Using data from two longitudinal surveys of American high school seniors, we show that basic cognitive skills had a larger impact on wages for 24-year-old men and women in 1986 than in 1978 For women, the increase in the return to cognitive skills between 1978 and 1986 accounts for all of the increase in the wage premium associated with post-secondary education. We also show that high school seniors' mastery of basic cognitive skills had a much smaller impact on wages two years after graduation than on wages six years after graduation.

Introduces the principles of survival analysis by showing their natural application to research questions about educational transitions. Way of asking questions about student droput and teacher attrition; Censoring as an analytic dilemma; Dissatisfaction with the dichotomization approach; Research on teacher career paths; Use of survival methods for analyzing student career data; More.

The vicarious emotional responses of macho and less macho males, as measured by the Hypermasculinity Inventory, were examined among 107 college males, who reported their emotions on arrival for the study and in response to viewing three videotapes of a crying, quiescent, and smiling baby, respectively. Subjects then completed the Hypermasculinity Inventory and the Sexual Experiences Survey. As predicted, macho males responded to the crying baby with more anger and less empathy than did less macho males. The results are discussed in terms of how macho males respond to distressing stimuli by inhibiting “feminine” emotions (e.g., empathy) and by amplifying “masculine” emotions (e.g., anger), thereby increasing the risk of aggressive behavior. [ABSTRACT FROM PUBLISHER]

Multiple-spell discrete-time survival analysis can be used to investigate the repeated occurrence of a single event, or the sequential occurrence of disparate events, including: students' and teachers' entries into, and exits from, school; childrens' progress through stages of cognitive reasoning; disturbed adolescents' repeated suicide attempts; and so forth. In this article, we introduce and illustrate the method using longitudinal data on exit from, and reentry into, the teaching profession. The advantages of the approach include: (a) applicability to many educational problems; (b) easy inclusion of time-invariant and time-varying predictors; (c) minimal assumptions-no proportional-hazards assumption is invoked and so the effects of predictors can vary over time within, and across, spells; and (d) all statistical models can be fit with a standard logistic regression package. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

Markedly different types of growth (learning) curves may generate indistinguishable covariance structures. We illustrate with an example of a 5 5 covariance matrix representing longitudinal measurements at five occasions. This example appears to conform closely to a simplex correlation pattern, and a simplex covariance structure provides an excellent fit (using LISREL V) to this covariance matrix. However, the (known) structure of this example differs greatly from the simplex model. In addition to indicating that an excellent fit of a simplex structure can be misleading, this example provides an opportunity to question common uses of covariance structure models for the study of growth. [ABSTRACT FROM PUBLISHER]

Many research questions in aging research treat time as the outcome variable. Researchers ask how much time must pass before a specific type of change or event occurs, and whether these times differ by characteristics of the subjects' background, training and treatment. Because of serious technical problems that arise when analyzing duration data, specially derived statistical methods -- the methods of survival analysis -- are required to answer the questions. In this paper, we introduce the conceptual framework of these new methodologies for analyzing duration data. We begin by identifying the types of research question that might appropriately treat time as an outcome. We then describe the new statistical methods for addressing such questions, provide a broad overview of their application, and identify relevant published sources containing additional background and technical information. [ABSTRACT FROM AUTHOR]

In the past decade the existence of individual differences in both rate and route of language development has been widely accepted. Some between-child differences are observed in the synchro nization of morphological with semantic skills. These differences are obscured by portmanteau measures like MLU. The purpose of this paper is to explore semantic and morphological predictors of MLU in order to identify individual variation in language development in a fairly large number of typically developing children. To accomplish this goal, we identified two additional variables: NPSAT, a measure of morphological skill, and MLU cw, a measure of utterance length in content words. A growth modelling strategy was used to identify both 'within-child' and 'between-child' differences in longitudinal data from 36 children. We found that typically developing children indeed use different strategies in lengthening their utterances. We therefore recommend caution in the use of MLU to 'language match' children when doing research on early language development. [ABSTRACT FROM PUBLISHER]

Attempts to determine whether enough qualified teachers will be available to staff the nation's schools in the coming years have been hampered by methodological difficulties that are inherent in the study of teacher career patterns. In this article, we have applied an analytic technique rarely used in educational research, proportional hazards modeling, to resolve these problems and to investigate the relationship between teachers' background characteristics and their career durations. We find that teacher demographic characteristics and subject specialty are important predictors of length of stay in teaching. Our results call into question several assumptions about teacher career persistence implicit in the national teacher supply and demand model. We also argue that proportional hazards modeling has wide applicability to many educational research questions. [ABSTRACT FROM PUBLISHER]