Abstract: This study investigated attrition in a 6-month physical activity intervention for older adults. The program was based on the social-cognitive theory incorporating self-efficacy factors. Two hundred forty-eight insufficiently active 65- to 74-year-olds were recruited from the Australian federal electoral roll. The intervention comprised walking and strength and flexibility exercises and was conducted in 30 local neighborhoods where the participants resided. Characteristics of individuals lost to attrition (n = 86, 35%) were compared with those of program completers (n = 162, 65%). Logistic-regression analysis showed that those lost to attrition came from areas of lower socioeconomic status, were overweight and less physically active, and had lower walking self-efficacy scores and higher loneliness scores. The results suggest that early assessment of these characteristics should be undertaken to identify individuals at risk of attrition, to improve retention, and to avoid potential bias.

Abstract: The constructs from A Neurolinguistic Theory of Bilingualism (Paradis 2004) that have implications for attrition are outlined and predictions are explored: The activation threshold hypothesis predicts that, all other factors being equal, language disuse leads to gradual loss; the most frequently used elements of L2 will replace their (less used) L1 counterparts; comprehension of forms will be retained longer than the ability to produce them. Elements sustained by declarative memory (e.g., vocabulary) are more vulnerable to attrition than those sustained by procedural memory (i.e., phonology, morphosyntax, lexicon). Declarative items are also more susceptible to interference (and hence to attrition by substitution) than implicit items. Pragmatics and conceptual representations are also modified by attrition. Motivation impacts the rate of attrition.

Abstract: We use data from the 1990/1994 Beginning Post-Secondary Survey to determine whether the factors associated with long-term attrition from higher education differ for students who initially enrolled part-time as compared to for students who initially enrolled full-time. Using a two-stage sequential decision model to analyze the initial enrollment intensity decision jointly with attrition, we find no evidence of correlation in the unobservables that necessitates joint estimation, but substantial evidence that the factors associated with attrition differ by initial enrollment status. The timing of initial enrollment, academic performance, parental education, household characteristics, and economic factors had a substantially greater impact on those initially enrolled full-time, while racial and ethnic characteristics had a greater impact on those initially enrolled part-time. The results of our study suggest that separate specifications are necessary to identify at-risk full-time as compared with at-risk part-time students.

Abstract: Education Policy Research Unit Division of Educational Leadership and Policy Studies College of Education, Arizona State University P.O. Box 872411, Tempe, AZ 852872411 Telephone: (480) 965-1886 Fax: (480) 965-0303 E-mail: epsl@asu.edu http://edpolicylab.org Education and the Public Interest Center School of Education, University of Colorado Boulder, CO 80309-0249 Telephone: (303) 492-8370 Fax: (303) 492-7090 Email: epic@colorado.edu http://education.colorado.edu/epic

Abstract: Background Attrition, which is virtually ubiquitous in randomized controlled clinical trials, introduces problems of increased bias and reduced statistical power. Although likelihood-based statistical models such as mixed-effects models can accommodate incomplete data, the assumption of ignorable attrition is usually required for valid inferences.Purpose In an effort to make the ignorability assumption more plausible, we consider the value of one readily obtained covariate that has been recommended by others, asking participants to rate their Intent to Attend the next assessment session.Methods Here we present a simulation study that compares the bias and coverage in mixed-effects outcome analyses that do and do not include Intent to Attend as a covariate.Results For the simulation specifications that we examined, the results are promising in the sense of reduced bias and greater precision. Specifically, if the time-varying Intent to Attend variable is associated with attrition, outcome and treatment grou...

Abstract: For some years now, and in most discussions of new teacher attrition, there has been a general belief that half of all new teachers fl ee the profession within fi ve years. Policy makers and practitioners are concerned about this apparent “crisis” in the teaching profession because they hear that (a) teachers’ skills improve during their fi rst two to three years of practice, and it seems a waste to lose so many entrants early in their careers, (b) the poorest and highest minority schools uniformly are more likely to have high turnover of new teachers, and (c) the production pipeline from teacher preparation programs is grossly ineffi cient in meeting the supply needs of our schools. This latter concern takes on added signifi cance because of an anticipated increase in demand for teachers stemming from high retirement rates among an aging teaching force in the United States. But the national evidence backing up some of these claims stems from sample data that are not representative of new teachers at the state level, and which cannot account for teachers who return to teaching after a gap in service.

Abstract: In this paper, we analyze magnitude and possible selectivity of attrition in first wave respondents in the Swiss Household Panel (SHP), from wave two (2000) through wave seven (2005). After comparing attrition of first wave respondents with that of other panel surveys, we proceed to model selectivity of attrition in two steps: we first build separate wave-to-wave models, and second a longitudinal all-wave model. The latter model includes wave interaction effects. The first models allow for tracing of selectivity development, i.e. whether an initial selectivity might compensate or cumulates over time, the second to assessing the effects of the covariates in a specific wave, controlling for the base attrition effect. In particular it allows for the analysis of consequences due to discrete fieldwork events. Our results support the findings in the literature: attritors are in general the younger people and the males, foreigners, the socially and politically “excluded”, i.e. those who show little social and political interest and participation, those who are mostly dissatisfied with various aspects in their life, and those who live in households with high unit nonresponse, and who exhibit a worse reporting behavior. This pattern is rather cumulative than compensating over panel waves. Excessive attrition in two waves presumably caused by two discrete events in the panel is not particularly selective. Still existing variation in selective attrition is worth to be further explored.

Abstract: Attrition, defined as a total loss to follow-up of participants, is a potential major bias in clinical trials. Participants can be lost for many reasons (death, illness, worsened health, refusal, withdrawal, lost to follow up). Attrition may be higher in older populations, so geriatric researchers should pay particular attention to the difficulties it raises. For a proper interpretation of research findings, a detailed analysis of the type of attrition observed and its possible determinants is essential, to determine if attrition has occurred at random or if it is associated to certain patient or treatment characteristics. This paper aims to review different causes of attrition, its prevalence among studies in different elderly populations, and its consequences on research findings. In addition, strategies used to minimise attrition (tracking, bonding, incentives) are discussed, and methods proposed to take this phenomenon into account are proposed.

Abstract: Using meta-analysis, randomized experiments in education that either clearly did or clearly did not experience student attrition were examined for the baseline comparability of groups. Results from 35 studies suggested that after attrition, the observed measures of baseline comparability of groups did not differ more than would be expected given sampling error. The degree of either overall or differential attrition did not relate to baseline comparability, a finding that held under sensitivity analyses. Also, both overall and differential attrition rates were unrelated to posttest effect sizes. All of these analyses, however, lacked sufficient statistical power to detect small but potentially meaningful effects. Results suggest caution is warranted when applying quality scales and other blanket rules pertaining to attrition that are meant to either serve as inclusion-exclusion criteria or in scoring study quality. Much greater attention is needed to both the reporting of attrition in primary studies and to the development of conceptual and empirical models of the attrition process. These developments would aid further investigation of the relation between attrition and study outcomes.

Abstract: This paper focuses on the relationship between institutional factors and the intention of undergraduate students to withdraw from or complete their distance education courses in the Arab Open University (AOU). The model was examine on a pilot sample of 127 students and then re-examined on the field study of 587 students. Mixed paradigms were selected, the quantitative approach was, the dominant technique, using factor analysis followed by discriminant analysis. The qualitative approach used content analysis for the in-depth interviews and open ended questions to explore the problem details. This study seems to suggest that, the intention to stay in the Arab Open University (AOU) distance learning (DL) programs depends critically on the quality of instructors and the variety of technology used to support and deliver these (DL) programs . Introduction Distance learning (DL) may be a new phenomenon in the developing economies but it is certainly not a new trend in the field of education in the developed economies such as the USA and the UK . In fact, distance learning can be traced back to the late 1800's when correspondence courses were first introduced ( Willis , 1994). Nowadays, there is a vast and rapid growth of distance learning at all levels of education to the extent that it moves from being a marginal to becoming an integral part of the overall educational and training provision ( Moore , 2002; UNESCO, 2002). This means that a significant number of learners all over the world receive their education by means of distance learning programs. Meanwhile, the recent advancements in technology offer many options for delivering and receiving education over geographic distances. Although it is clear that DL widens the scope of educational opportunities for those learners who already have an access to educational facilities, the high attrition in DL universities is regarded as a dilemma for which an appropriate solution has yet to be found. Problem Definition It has always been the concern of educators to retain the greatest possible number of learners in distance learning. The percentage of students who withdrew from traditional higher education remained steady between 40-45% over the past 100 years (Tinto V., 1982). In the context of online learning, some scholars found that the attrition rate of distance learning students is significantly higher than that in traditional classes ( Carr , 2000; Diaz , 2002; Frankola, 2001 ) . Student retention and attrition rates have all along been a concern of administrators of educational and training institutions in not only Asia and Latin America but also, as pointed out by Rwegasira (1988), in Africa . This problem is, in this research, re-examined in the context of the Arab world. Do the factors, which account for this phenomenon in the Middle East , differ from what has been found elsewhere? In addition, if so how and what are the theoretical and policy implications? The major problem discussed and hence analysed in this research is: Why do students fail to complete their distance learning programs and thus fail to persist with the degree completion or fulfilment of their educational goals? A variety of terms has been used to describe non-completion and these terms have been defined in different ways in different education sectors (McGivney, 2004). Gallie (2005) defines attrition as the number of students at the start of the course minus those who complete the course. Attrition refers to the decrease in the number of students enrolled in some courses; and such decrease can be attributed to one reason or another. Attrition may refer to stop-outs or dropouts. Stop-outs are those students who leave universities and return to it sometime later. Dropouts are students who leave and do not return to universities. According to Astin (1970) , students cannot be classified as dropouts until they die. An antonym of attrition is retention. Retention describes students who are promoted from one phase of education to the next and are enrolled over a considerable period ( Martinez , 2004). In this study, and fo r the purposes of developing a model of attrition of students in distance learning, a dropout is considered any student who is enrolled at an Arab Open University (AOU) for one semester but does not intend to be enrolled the next semester. Retention will be any student who is enrolled at an AOU for one semester and intends to continue to be enrolled the next semester. Attrition or retention is the predicted or the dependent variable. There are many independent variables or the predictors, which are responsible for either attrition or retention . In this study, we are interested in institutional variables either social or academic. The model developed is based on intentions of the students to leave or stay in the program rather than actual numbers of stop-outs or drop-outs. The predictions of a model based on intentions are likely to give opportunities and time for remedial actions for pre-emption of the attrition problem.

Abstract: Long term bilingual immigrants often report that they perceive first language attrition after years of living in a second language surrounding. This paper focuses on the individual’s own perception concerning first language attrition and identity. It deals with questions such as: To what extent does living in another country and speaking another language influence one’s mother tongue? If individuals experience first language attrition, do they really ‘suffer’ from it? Is there any objective evidence for their supposed decline of language skills? Data from a study of attrition in German migrants in the Netherlands will be discussed, showing the close relation between language (decline) and identity as a result of interacting factors over the lifespan.

Abstract: To enhance student performance, prevent attrition, and build a learning community, two courses were linked together by requiring concurrent enrollment. Students in an unlinked class were used as a comparison group. Grades, evaluations, and attrition rate suggest that linking courses can improve writing and exam scores and reduce attrition.

Abstract: Introduction: While it is known that a significant proportion of students within the higher education system do not graduate as expected, knowledge about student attrition in pharmacy is limited. A greater understanding of attrition rates will allow workforce planners and policy makers to estimate the number of new pharmacists that can be expected to join the register each year. Aim: This paper aims to provide information on attrition among pharmacy students in the UK. Method: Data are collated from a range of sources to explore trends or patterns in attrition according to factors such as gender, institution and student type. Results: Between the years 1994 and 2000 overall attrition reached a peak (19%) in 1997, although time series analysis found no significant trend ( p = 0.612). Attrition rates vary by institution, overseas compared with home students and male students compared with females are at greater risk of dropping out. Conclusion: Changes to the way in which student data are collected are recommended, as it is currently difficult to track a cohort with absolute certainty. Nevertheless, the paper draws attention to the extent to which attrition from the pharmacy degree occurs, enabling workforce planners to estimate future intake onto the professional register.

Abstract: Sample attrition, a major concern in any longitudinal study, is even more problematic when adolescents are the study population. The need to minimize the loss of participants in order to maintain t...

Abstract: THE PROJECT described in this article seeks to utilize a complex set of variables and characteristics, including data mined from an administration of the College Student Experiences Questionnaire, to determine the specific risk of attrition of individual college students prior to their matriculation, permitting specific and personal interventions. Student persistence is a matter of concern at almost all institutions of higher education, as well as to legislators, government officials, and the public. While some student attrition is not necessarily a negative outcome, the wasted resources and perceptions of failure that are associated with unacceptable attrition levels are problematic for college and university administrators. Many institutions have implemented strategies intended to enhance student persistence. However, most involve the broad application of programs, services, or instructional initiatives that affect large groups of students. Because it is reasonable to expect that some portion of any group of students would have been retained regardless of the intervention, such a broad approach is, at best, inefficient. The project described in this article seeks to utilize a complex set of variables and characteristics to determine the specific risk of attrition of individual students prior to their matriculation. For those determined to be most at risk, an intervention specific to the individual student and his or her risk factors will be implemented. BACKGROUND A number of studies of student persistence have examined the interaction between students and institutions. Tinto (1975) proposes a predictive model based upon principles of the student's level of academic and social integration. The model appears very useful in explaining attrition in the second year of college and beyond. However, decades of evidence suggest that attrition is greatest during the first year of college, as demonstrated by Iffert (1958), Marsh (1966), andEckland (1964). Pascarella and Terenzini (1980) applied Tintos principles of academic and social integration of students in the first year of college. They found evidence to support the basic aspects of the Tinto model - particularly the value of interaction between students and faculty members. Tintos research and that of Pascarella and Terenzini are useful models for predicting attrition based upon student characteristics and the nature and extent of student interaction with the institution. Chapman and Pascarella (1983) studied differences in student social and academic integration, central principles in Tintos work, across various types of institutions. The researchers controlled for differences in student characteristics and found that there were differences across institutional type regarding both social and academic integration. The results suggest that particular types of institutions foster different sorts of integration or interaction opportunities for students. Robbins, Allen, Cassilas & Peterson (2006) studied the effect of student self-reported psychosocial factors on college outcomes in the first year and also found differences across institutional type. Braxton, Vesper, and Hossler (1995) studied students' expectations of the college experience and the relationship of those expectations to students' intention to persist across a number of institutions. The study demonstrated that the extent to which student expectations of their experience are met has an effect on their plans to continue their matriculation. Heiland, Stallings, and Braxton (2002) also studied how the fulfillment of student expectation relates to social integration and student departure. Their study at a single institution concluded that the satisfaction of student expectations plays a substantial role in student departure. In a study at Canisius College, a smaller institution, Glynn, Sauer, and Miller (2003) developed a model for predicting attrition based upon pre-matriculation characteristics and opinions. …

Abstract: This paper identifies research work undertaken in 2002 that examined the notion of why first year students leave university. Utilising a case study approach, this research identified students enrolled in three foundation year courses in science. To demonstrate the context of attrition at a regional university, student data were extrapolated and examined. Difficulty arose when defining the parameters of attrition as processes to enhance retention became fuzzier. The social and educational influences surrounding attrition were considered an important factor in persistence of academic work and study. The paper reinforces the seminal work done by Yorke (1998), and through recommendations identifies the interrelationships among the institutions, its staff, the pedagogy and student responsibilities within the learning journey.

Abstract: Over the past decades there has been an increasing use of panel surveys at the household or individual level, instead of using independent cross-sections. Panel data have important advantages, but there are also two potential drawbacks: attrition bias and panel conditioning effects. Attrition bias can arise if respondents drop out of the panel non-randomly, i.e., when attrition is correlated to a variable of interest. Panel conditioning arises if responses in one wave are in?uenced by participation in the previous wave(s). The experience of the previous interview(s) may affect the answers of respondents in a next interview on the same topic, such that their answers differ systematically from the answers of individuals who are interviewed for the first time. The literature has mainly focused on estimating attrition bias; less is known on panel conditioning effects. In this study we discuss how to disentangle the total bias in panel surveys due to attrition and panel conditioning into a panel conditioning and an attrition effect, and develop a test for panel conditioning allowing for non-random attrition. First, we consider a fully nonparametric approach without any assumptions other than those on the sample design, leading to interval identification of the measures for the attrition and panel conditioning effect. Second, we analyze the proposed measures under additional assumptions concerning the attrition process, making it possible to obtain point estimates and standard errors for both the attrition bias and the panel conditioning effect. We illustrate our method on a variety of questions from two-wave surveys conducted in a Dutch household panel. We found a significant bias due to panel conditioning in knowledge questions, but not in other types of questions. The examples show that the bounds can be informative if the attrition rate is not too high. Point estimates of the panel conditioning effect do not vary a lot with the different assumptions on the attrition process.

Abstract: Tooth wear is a common phenomenon in archaeological material. It has been related to the abrasiveness of diet and to the tribological attrition of teeth of individuals. Numerous investigations have been carried out in north and middle American samples as well as African anthropological material. Not much is known about tooth wear in European cultures. Eleven skulls from Chervona Gusarovka, and 14 skulls from the Upper Saltov sites of the Khazar Kaganat region (8th–10th centuries AD) in eastern Ukraine, with different diets were examined. A total of 208 teeth were studied for tooth wear, caries prevalence and periodontal status. Abrasion grades were determined according to a standardised classification and statistically evaluated. Periodontal status was measured using the distance between the enamel-cementum junction and alveolar crest and the gingival attachment level respectively. Tooth wear was significantly different (P < 0.01) between the two populations. A low caries prevalence of 4.2% in the Chervona Gusarovka population and 1.7% in the Upper Saltov population was found. Significantly more alveolar crest bone resorption on the lingual side was found in the premolars and anterior teeth of the Chervona Gusarovka population. No significant differences were found regarding gingival attachment levels and gingival recession. It is concluded that the content and mode of food preparation influenced tooth wear, as reflected by the prevalence of dental caries and periodontal diseases in these ancient populations. Copyright © 2006 John Wiley & Sons, Ltd.

Abstract: This thesis explores L1 attrition among young Korean-English late bilinguals. Thirty Korean immigrants to New Zealand, who had arrived at the age of 12-13 years and had spent at least 2 years in New Zealand, participated in the study. Ten monolingual Korean children aged 12 years served as a comparison group for L1 data. Linguistic data in both L1 and L2 were elicited by a standardised picture-naming test and a story-retelling task supplemented by a stimulated recall protocol. Information related to social variables and language use patterns was elicited through a questionnaire and interviews. Skehan (1996; 1998; 2001) proposes three dimensions of linguistic performance??? accuracy, fluency, and complexity. The general findings suggest that accuracy and lexical diversity in L1 are most susceptible to attrition and that there is general positive transfer from L1 to L2 skills. While there is no direct negative interaction between L1 and L2 proficiency, analysis reveals that increasing L2 fluency and a decrease in L1 use have possible indirect effects on attrition in L1 accuracy but not in L1 lexical diversity. The data suggest that, while the frequency of return visits to the homeland is an important social variable, language use involving the father and siblings is also an important factor in attrition or maintenance of L1 proficiency of adolescent late bilinguals. Qualitative analysis conducted on five cases corroborates the quantitative findings. Analyses of speech samples reveal that synthetic structures with semantic ambiguity are most susceptible to L1 attrition. The qualitative analysis also highlights the role of L2 socialisation in L1 attrition in adolescent immigrant children who negotiate their language use and identities in an L2-dominant environment and show different patterns of attrition in their L1.

Abstract: This study aimed at investigating L2 attrition of vocabulary in adult Iranian learners of English at four different proficiency levels. A 40-item vocabulary test measured their productive and receptive vocabulary in and out of context for concrete and abstract nouns with different frequencies. After an interval of 3 months, subjects took the same test. The results revealed that there is no significant difference between the attrition rate of concrete and abstract nouns across different proficiency levels. Moreover, advanced learners who did not participate in classes and had no exposure to English throughout the 3 months interval demonstrated a significant amount of attrition in non- contextualized nouns. Besides, those learners who continued participating in English classes demonstrated attrition in receptive vocabulary but advanced non-continuing learners underwent attrition in productive vocabulary. Additionally, both continuing and non- continuing learners except advanced ones underwent attrition in low-frequency nouns. These findings suggest that certain words are more vulnerable to attrition and that even learners who are still in the process of learning English are susceptible to it.

Abstract: Publisher Summary This chapter provides an overview of attrition studies in systems with homogeneous distribution and jet distribution of the fluidizing gas. The chapter addresses principal causes and hydrodynamics resulting in particle attrition in major fluidized bed applications. Attrition is commonly defined as undesired particle breakage, sometimes as erosive wear—that is, a superficial size reduction process in a sheared environment. Fluidization is the term used to denote the fluid-like behavior of powders induced by the flow of an interstitial fluid (gas or liquid). Attrition by surface abrasion generates fine particles that are quickly elutriated. This breakage process is essentially related to the occurrence of surface wear as the emulsion phase of the fluidized bed is sheared by the passage of bubbles. Attrition by surface abrasion of sorbents under reactive conditions displays a complex phenomenology, which results from conflicting effects of particle calcination and sulphation. More fundamental understanding of attrition in fluidized beds requires a more rigorous modelling, coupled with reliable kinetic data on the rate of particle attrition. The application of distinct element method may provide this capability in the long term. In the short term the use of population balance models, coupled with proven reliable breakage kernels may provide helpful insights for controlling the attrition process in fluidized beds.