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Hierarchical Linear Models (hierarchical + linear_models)

Distribution by Scientific Domains

Medical Sciences	40%
Psychology	20%
Humanities and Social Sciences	20%

Selected Abstracts

Impact of Scribes on Performance Indicators in the Emergency Department

ACADEMIC EMERGENCY MEDICINE, Issue 5 2010
Rajiv Arya MD
Abstract Objectives:, The objective was to quantify the effect of scribes on three measures of emergency physician (EP) productivity in an adult emergency department (ED). Methods:, For this retrospective study, 243 clinical shifts (of either 10 or 12 hours) worked by 13 EPs during an 18-month period were selected for evaluation. Payroll data sheets were examined to determine whether these shifts were covered, uncovered, or partially covered (for less than 4 hours) by a scribe; partially covered shifts were grouped with uncovered shifts for analysis. Covered shifts were compared to uncovered shifts in a clustered design, by physician. Hierarchical linear models were used to study the association between percentage of patients with which a scribe was used during a shift and EP productivity as measured by patients per hour, relative value units (RVUs) per hour, and turnaround time (TAT) to discharge. Results:, RVUs per hour increased by 0.24 units (95% confidence interval [CI] = 0.10 to 0.38, p = 0.0011) for every 10% increment in scribe usage during a shift. The number of patients per hour increased by 0.08 (95% CI = 0.04 to 0.12, p = 0.0024) for every 10% increment of scribe usage during a shift. TAT was not significantly associated with scribe use. These associations did not lose significance after accounting for physician assistant (PA) use. Conclusions:, In this retrospective study, EP use of a scribe was associated with improved overall productivity as measured by patients treated per hour (Pt/hr) and RVU generated per hour by EPs, but not as measured by TAT to discharge. ACADEMIC EMERGENCY MEDICINE 2010; 17:490,494 © 2010 by the Society for Academic Emergency Medicine [source]

Scales of association: hierarchical linear models and the measurement of ecological systems

ECOLOGY LETTERS, Issue 6 2007
Sean M. McMahon
Abstract A fundamental challenge to understanding patterns in ecological systems lies in employing methods that can analyse, test and draw inference from measured associations between variables across scales. Hierarchical linear models (HLM) use advanced estimation algorithms to measure regression relationships and variance,covariance parameters in hierarchically structured data. Although hierarchical models have occasionally been used in the analysis of ecological data, their full potential to describe scales of association, diagnose variance explained, and to partition uncertainty has not been employed. In this paper we argue that the use of the HLM framework can enable significantly improved inference about ecological processes across levels of organization. After briefly describing the principals behind HLM, we give two examples that demonstrate a protocol for building hierarchical models and answering questions about the relationships between variables at multiple scales. The first example employs maximum likelihood methods to construct a two-level linear model predicting herbivore damage to a perennial plant at the individual- and patch-scale; the second example uses Bayesian estimation techniques to develop a three-level logistic model of plant flowering probability across individual plants, microsites and populations. HLM model development and diagnostics illustrate the importance of incorporating scale when modelling associations in ecological systems and offer a sophisticated yet accessible method for studies of populations, communities and ecosystems. We suggest that a greater coupling of hierarchical study designs and hierarchical analysis will yield significant insights on how ecological processes operate across scales. [source]

Community alcohol outlet density and underage drinking

ADDICTION, Issue 2 2010
Meng-Jinn Chen
ABSTRACT Aim This study examined how community alcohol outlet density may be associated with drinking among youths. Methods Longitudinal data were collected from 1091 adolescents (aged 14,16 at baseline) recruited from 50 zip codes in California with varying levels of alcohol outlet density and median household income. Hierarchical linear models were used to examine the associations between zip code alcohol outlet density and frequency rates of general alcohol use and excessive drinking, taking into account zip code median household income and individual-level variables (age, gender, race/ethnicity, personal income, mobility and perceived drinking by parents and peers). Findings When all other factors were controlled, higher initial levels of drinking and excessive drinking were observed among youths residing in zip codes with higher alcohol outlet densities. Growth in drinking and excessive drinking was, on average, more rapid in zip codes with lower alcohol outlet densities. The relation of zip code alcohol outlet density with drinking appeared to be mitigated by having friends with access to a car. Conclusion Alcohol outlet density may play a significant role in initiation of underage drinking during early teenage, especially when youths have limited mobility. Youth who reside in areas with low alcohol outlet density may overcome geographic constraints through social networks that increase their mobility and the ability to seek alcohol and drinking opportunities beyond the local community. [source]

Scales of association: hierarchical linear models and the measurement of ecological systems

Acculturation and Latino Family Processes: How Cultural Involvement, Biculturalism, and Acculturation Gaps Influence Family Dynamics,

FAMILY RELATIONS, Issue 3 2008
Paul R. Smokowski
Abstract: This study investigated how adolescent and parent acculturation (culture-of-origin and U.S. cultural involvement, biculturalism, acculturation conflicts, and parent-adolescent acculturation gaps) influenced family dynamics (family cohesion, adaptability, familism, and parent-adolescent conflict) in a sample of 402 Latino families from North Carolina and Arizona. Multiple regression and hierarchical linear models suggested that culture-of-origin involvement and biculturalism were cultural assets related to positive outcomes, whereas acculturation conflict was inversely related to positive family dynamics and positively related to parent-adolescent conflict. Parent-adolescent acculturation gaps were inversely associated with family cohesion, adaptability, and familism but were unrelated to parent-adolescent conflict. Limitations and implications for practice are discussed. [source]

LEADERSHIP AND SEX-SIMILARITY: A COMPARISON IN A MILITARY SETTING

PERSONNEL PSYCHOLOGY, Issue 2 2007
ROBERT P. VECCHIO
In a study of the possible impact of leader and follower sex-similarity on leadership criteria, survey responses of 1,974 military cadets in 167 squads were analyzed at the completion of a month-long field training exercise. Analyses (which included a series of hierarchical linear models that explicitly accounted for the nested character of squad membership relative to a leader) yielded results that indicated that same-sex leader,subordinate pairings had more positive working relationships than different-sex pairings. However, leader ratings of subordinate performance did not yield clear evidence of such an effect. In addition, increases in the proportion of female members in a squad were not associated with differences in squad-level cohesion, while being associated with decreases in squad-level leader,member exchange (LMX). Subordinate reports of participation in decision making, although correlated positively with LMX, were not significantly different as a function of leader,subordinate sex-similarity. Implications are derived for managing demographic diversity in order to enhance within-unit functioning. [source]

The Course and Quality of Intimate Relationships Among Psychologically Distressed Mothers

AMERICAN JOURNAL OF ORTHOPSYCHIATRY, Issue 1 2010
Lauren M. Papp
The longitudinal course and quality of intimate relationships were tested in relation to maternal depressive symptoms in a sample of 1,275 families from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development. Assessments of mothers' intimate relationship status, intimate relationship quality, and depressive symptoms were obtained on 11 occasions from the birth of a child through age 15. Consistent with predictions, results from hierarchical linear models indicated that maternal depressive symptoms over time were associated with a lower probability of being married and lower levels of relationship quality. The strength of the association between relationship quality and depression was stronger than the linkage between relationship course and depression. Sociodemographic characteristics (e.g., mother age, child gender, ethnicity) were more predictive of trajectories of relationship course than relationship quality. Findings are discussed in terms of efforts to prevent and treat the longitudinal interplay between poor intimate relationship functioning and partners' psychopathology and its implications for the overall health and well-being of parents, couples, and children. [source]

Utility of Crossover Designs in Clinical Trials: Efficacy of Desipramine vs.

THE AMERICAN JOURNAL ON ADDICTIONS, Issue 2 2002
Placebo in Opioid-Dependent Cocaine Abusers
The utility of the crossover design in substance abuse research was examined in a 26-week, double-blind clinical trial that evaluated the efficacy of desipramine (0 or 150 mg/day) in 109 male and female cocaine- and opiate-dependent patients maintained on buprenorphine (12 mg/day) or methadone (65 mg/day). After being stabilized on buprenorphine or methadone (weeks 1,2), half of the patients were randomly assigned to receive desipramine for the first half of the trial and placebo for the second, with the order reversed for the second half. Analyses using hierarchical linear models (HLM) indicated that desipramine reduced the use of opiates only when administered at the start (rather than the middle) of the trial, whereas cocaine use was reduced when desipramine was introduced at either time. [source]

Economic Inequality and Intolerance: Attitudes toward Homosexuality in 35 Democracies

AMERICAN JOURNAL OF POLITICAL SCIENCE, Issue 4 2008
Robert Andersen
Using hierarchical linear models fitted to data from the World Values Survey and national statistics for 35 countries, this article builds on the postmaterialist thesis by assessing the impact of economic inequality across and within nations on attitudes toward homosexuality. It provides evidence that tolerance tends to decline as national income inequality rises. For professionals and managers, the results also support the postmaterialist argument that economic development leads to more tolerant attitudes. On the other hand, attitudes of the working class are generally less tolerant, and contrary to expectations of the postmaterialist thesis, are seemingly unaffected by economic development. In other words, economic development influences attitudes only for those who benefit most. These findings have political implications, suggesting that state policies that have the goal of economic growth but fail to consider economic inequality may contribute to intolerant social and political values, an attribute widely considered detrimental for the health of democracy. [source]

Typology and psychological effects of adolescents' interpersonal relationships in Taiwan

ASIAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 2 2009
Yuh-Huey Jou
The present research explored Taiwanese adolescent students' interpersonal relationships and examined whether teachers' evaluations of these students' health and academic performances varied with the students' interpersonal relationship patterns. Data (n = 2310) were based on a panel study conducted by the Taiwan Youth Project in 2001 (eighth grade) and 2002 (ninth grade). Latent class models and hierarchical linear models were used to analyse the data. Adolescent students' interpersonal relationships were categorized as Multiple Contacts, Parents- and Peers-Close, Peers-Close, and Few Contacts. The research results showed that not only adolescents' self-reports of self-esteem and depressed mood but also teachers' evaluations of adolescents' health and academic performances varied with adolescents' interpersonal relationship patterns. An influence of teachers' character and work environment on their evaluations of students was found. Teachers who had more years of teaching and higher job satisfaction rated their students as having better health, and teachers who felt greater respect from their students reported that their students had better academic performance. The connection between adolescents' psychological well-being and the roles of parents, peers and teachers is also discussed. [source]