Two-Level Proportional Hazards Models

We extend the proportional hazards model to a two-level model with a random intercept term and random coefficients. The parameters in the multilevel model are estimated by a combination of EM and Newton-Raphson algorithms. Even for samples of 50 groups, this method produces estimators of the fixed effects coefficients that are approximately unbiased and normally distributed. Two different methods, observed information and profile likelihood information, will be used to estimate the standard errors. This work is motivated by the goal of understanding the determinants of contraceptive use among Nepalese women in the Chitwan Valley Family Study (Axinn, Barber, and Ghimire, 1997). We utilize a two-level hazard model to examine how education and access to education for children covary with the initiation of permanent contraceptive use.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65551/1/j.0006-341X.2002.00754.x.pd

Frenectomy for improvement of a problematic conventional maxillary complete denture in an elderly patient: a case report

Maxillary labial and buccal frena are considered as normal anatomic structures in the oral cavity. However, they may exist intraorally as a thick broad fibrous attachment and/or become located near the crest of the residual ridge, thus interfering with proper denture border extension resulting in inferior denture stability, retention and overall patient satisfaction. This case report highlights the importance of clinical examination and treatment planning which may mandate preprosthetic surgery prior to fabrication of a new conventional complete denture. Adequate patient satisfaction with conventional complete dentures can be significantly increased after frenectomy

Ascertainment of occupational histories in the working population: The occupational history calendar approach

Background Self-reported occupational histories are an important means for collecting historical data in epidemiological studies. An occupational history calendar (OHC) has been developed for use alongside a national occupational hazard surveillance tool. This study presents the systematic development of the OHC and compares work histories collected via this calendar to those collected via a traditional questionnaire. Methods The paper describes the systematic development of an OHC for use in the general working population. A comparison of data quality and recall was undertaken in 51 participants where both tools were administered. Results TheOHCenhanced job recall compared with the traditional questionnaire. Good agreement in the data captured by both tools was observed, with the exception of hazard exposures. Conclusions A calendar approach is suitable for collecting occupational histories from the general working population. Despite enhancing job recall the OHC approach has some shortcomings outweighing this advantage in large-scale population surveillance

Modifying and validating the Composite International Diagnostic Interview (CIDI) for use in Nepal

Background : Efforts to develop and validate fully‐structured diagnostic interviews of mental disorders in non‐Western countries have been largely unsuccessful. However, the principled methods of translation, harmonization, and calibration that have been developed by cross‐national survey methodologists have never before been used to guide such development efforts. The current report presents the results of a rigorous program of research using these methods designed to modify and validate the Composite International Diagnostic Interview (CIDI) for an epidemiological survey in Nepal. Methods : A five‐step process of translation, harmonization, and calibration was used to modify the instrument. A blinded clinical reappraisal design was used to validate the instrument. Results : Preliminary interviews with local mental health expert led to a focus on major depressive episode, mania/hypomania, panic disorder, post‐traumatic stress disorder, generalized anxiety disorder, and intermittent explosive disorder. After an iterative process of multiple translations‐revisions guided by the principles developed by cross‐national survey methodologists, lifetime DSM‐IV diagnoses based on the final Nepali CIDI had excellent concordance with diagnoses based on blinded Structured Clinical Interview for DSM‐IV (SCID) clinical reappraisal interviews. Conclusions : Valid assessment of mental disorders can be achieved with fully‐structured diagnostic interviews even in low‐income non‐Western settings with rigorous implementation of replicable developmental strategies. Copyright © 2013 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97206/1/mpr1375.pd

Spousal Communication and Contraceptive Use in Rural Nepal: An Event History Analysis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97198/1/j.1728-4465.2011.00268.x.pd

Antecedents to export information generation: a cross-national study

Purpose ─ The objective of this study is to examine the factors that enhance export decision-makers’ generation of export information, using a non-linear approach and a multi-country context, and so provide export decision-makers with empirically-based guidelines on how to maximize their information acquisition efforts. Design/methodology/approach ─ A broad perspective on export information generation is adopted, including marketing research, export assistance and market intelligence. The model of antecedents to information generation is tested in three studies (US, Austria, New Zealand, respectively) using structural equation modeling techniques. Multigroup and hierarchical analysis is performed to assess cross-national invariance of relevant measures, and quadratic effects. Findings ─ The findings show that the predictors of export information generation vary across the three countries studied, and that many of the relationships are non-linear. Research limitations/implications ─This study contributes to the export marketing literature by developing our understanding of how exporters can develop greater knowledge of information sources on which to build export decisions, and the conditions necessary for enhanced export information acquisition activity. The findings highlight that future research should consider non-linear relationships and the examination of the outcomes of export information generation in a cross-national setting. Practical implications ─ The study findings advocate that practitioners (exporters and advisers) tailor their export information generation efforts to the different country needs. Originality/value ─ This research responds to a call for more theoretically-based studies on antecedents to export information generation, concurrent with the use of more robust statistical methods

Maximizing Data Quality using Mode Switching in Mixed-Device Survey Design: Nonresponse Bias and Models of Demographic Behavior

Conducting survey interviews on the internet has become an attractive method for lowering data collection costs and increasing the frequency of interviewing, especially in longitudinal studies. However, the advantages of the web mode for studies with frequent re-interviews can be offset by the serious disadvantage of low response rates and the potential for nonresponse bias to mislead investigators. Important life events, such as changes in employment status, relationship changes, or moving can cause attrition from longitudinal studies, producing the possibility of attrition bias. The potential extent of such bias in longitudinal web surveys is not well understood. We use data from the Relationship Dynamics and Social Life (RDSL) study to examine the potential for a mixed-device approach with active mode switching to reduce attrition bias. The RDSL design allows panel members to switch modes by integrating telephone interviewing into a longitudinal web survey with the objective of collecting weekly reports. We found that in this design allowing panel members to switch modes kept more participants in the study compared to a web only approach. The characteristics of persons who ever switched modes are different than those who did not – including not only demographic characteristics, but also baseline characteristics related to pregnancy and time-varying characteristics that were collected after the baseline interview. This was true in multivariate models that control for multiple of these dimensions simultaneously. We conclude that mode options and mode switching is important for the success of longitudinal web surveys to maximize participation and minimize attrition

Collecting Survey Data during Armed Conflict

Surveys provide crucial information about the social consequences of armed conflict, but armed conflict can shape surveys in ways that limit their value. We use longitudinal survey data from throughout the recent armed conflict in Nepal to investigate the relationship between armed conflict events and survey response. The Chitwan Valley Family Study (CVFS) provides a rare window into survey data collection through intense armed conflict. The CVFS data reveal that with operational strategies tailored to the specific conflict, duration of the panel study is the main determinant of attrition from the study, just as in most longitudinal studies outside of conflict settings. Though minor relative to duration, different dimensions of armed conflict can affect survey response in opposing directions, with bombings in the local area reducing response rates but nationwide political events increasing response rates. This important finding demonstrates that survey data quality may be affected differently by various dimensions of armed conflict. Overall, CVFS response rates remained exceptionally high throughout the conflict. We use the CVFS experience to identify principles likely to produce higher quality surveys during periods of generalized violence and instability