819 resultados para Inimizes the chi-square


Relevância:

100.00% 100.00%

Publicador:

Resumo:

A associação entre fatores de risco cardiovascular (FRCV) na pósmenopausa e o antecedente de irregularidade menstrual no menacme foi avaliado em estudo caso-controle envolvendo 414 mulheres na pósmenopausa com idade de 60,4 ± 5,5 anos e IMC de 25,3 ± 4,7 kg/m2. As variáveis consideradas foram: caracterização do ciclo menstrual entre 20 e 35 anos (independente) e relato atual sobre ocorrência de hipertensão arterial, dislipidemia, diabetes mellitus e doença arterial coronariana (dependentes). Utilizou-se o teste qui-quadrado e modelos de regressão logística, ajustados para outras variáveis implicadas no risco para doenças CV, com nível de significância 5%. Observou-se que mulheres que relataram irregularidade menstrual prévia estiveram associadas com risco aumentado para ocorrência de algum FRCV [odds ratio ajustado (OR)= 2,14; IC-95%= 1,02–4,48], quando comparadas àquelas com ciclos regulares. Análise estratificada demonstrou as seguintes associações significativas com o antecedente de irregularidade menstrual: hipertensão arterial (OR= 2,4; 95% IC= 1,39–5,41), hipercolesterolemia (OR= 2,32; 95% IC= 1,17–4,59), hipertrigliceridemia (OR= 2,09; 95% IC= 1,10–4,33) e angioplastia coronariana (OR= 6,82; 95% IC= 1,44–32,18). Os dados sugerem que o antecedente de irregularidade menstrual, indicativo da ocorrência da síndrome dos ovários policísticos na idade reprodutiva, pode estar relacionado com aumento do risco para doenças CV na pós-menopausa __________________________________________________ABSTRACT Menstrual Cycle Irregularity as a Marker of Cardiovascular Risk Factors at Postmenopausal Years.To evaluate the association between cardiovascular risk factors (CVRF)during postmenopausal years and previous menstrual irregularity during reproductive years, we performed a case-control study in 414 postmenopausal women (mean age 60.4 ± 5.5 years; BMI 25.3 ± 4.7 kg/m2). The variables assessed were: menstrual cycle characteristics at age 20–35y (independent) and records of arterial hypertension, dyslipidemia, diabetes mellitus, and coronary heart disease (dependent). Statistical analysis used the chi-square test and logistic regression, adjusting for potential confounders for cardiovascular risk, with significance set at 5%. Women reporting previous menstrual irregularity were associated with increased risk for some CVRF [adjusted odds ratio (OR) 2.14; CI-95%= 1.02–4.48], when compared with those reporting regular menstrual cycles. Stratified analysis demonstrated significant associations of previous menstrual irregularity with: arterial hypertension [OR= 2.74; CI-95%= 1.39–5.41), hypercholesterolemia (OR= 2.32; CI-95%= 1.17–4.59), hypertriglyceridemia (OR= 2.09; CI-95%=1.10–4.33), and coronary angioplasty (OR= 6.82; CI-95%= 1.44–32.18). These data suggest that a prior history of menstrual irregularity, as indicative of polycystic ovary syndrome, may be related to increased risk for CVD during postmenopausal years

Relevância:

100.00% 100.00%

Publicador:

Resumo:

FERNANDES, Marcos Henrique; ROCHA, Vera Maria da; RONCALLI, Angelo Giuseppe. Fatores Associados à Prevalência de Sintomas Osteomusculares em Professores. Revista de salud pública, v. 11, n. 2, p. 256-267, 2009.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This study aimed to analyze the leadership style adopted by managers of nongovernmental organizations in the metropolitan region of Belem on the theory of Hersey and Blanchard. This theory is called situational leadership ranks E1, E2, E3, E4 and the styles of leadership and maturity in parallel classes M1, M2, M3 and M4. This study examined the relationship of leadership styles with the maturity of work, identified the relationship of leadership styles as related to psychological maturity and job maturity and psychological maturity. The main objectives were to analyze and relate leadership styles with the maturity of the leaders and understand the phenomenon of leadership from the self-perception of those who lead the organizations studied. To achieve the objectives we used a questionnaire already validated the theory of situational leadership and applied in 320 non-governmental organizations in the metropolitan region of Belem The methodology was quantitative, descriptive and exploratory. The analysis was by descriptive statistics and inferential statistics for univariate and bivariate form, applying the chi-square, the V Crammer and Spearman correlation. The data analysis shows safety, attested to the frequencies, and average margin of error and after application of the tests it was found that a relationship between the leadership style of work with the maturity and psychological maturity. The managers of nongovernmental organizations practicing various styles of leadership and focus on the quadrant of high maturity. It was diagnosed when the manager uses only one style of leadership was the predominance of E3 "share or support", which represents 24% of the sample. As uses two styles of leadership is the predominance of E3 and E2, which represents 76%. So the managers of nongovernmental organizations in the metropolitan region of Belem, practicing a style of leadership support, sharing ideas for decision making using a democratic style

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A associação entre fatores de risco cardiovascular (FRCV) na pósmenopausa e o antecedente de irregularidade menstrual no menacme foi avaliado em estudo caso-controle envolvendo 414 mulheres na pósmenopausa com idade de 60,4 ± 5,5 anos e IMC de 25,3 ± 4,7 kg/m2. As variáveis consideradas foram: caracterização do ciclo menstrual entre 20 e 35 anos (independente) e relato atual sobre ocorrência de hipertensão arterial, dislipidemia, diabetes mellitus e doença arterial coronariana (dependentes). Utilizou-se o teste qui-quadrado e modelos de regressão logística, ajustados para outras variáveis implicadas no risco para doenças CV, com nível de significância 5%. Observou-se que mulheres que relataram irregularidade menstrual prévia estiveram associadas com risco aumentado para ocorrência de algum FRCV [odds ratio ajustado (OR)= 2,14; IC-95%= 1,02–4,48], quando comparadas àquelas com ciclos regulares. Análise estratificada demonstrou as seguintes associações significativas com o antecedente de irregularidade menstrual: hipertensão arterial (OR= 2,4; 95% IC= 1,39–5,41), hipercolesterolemia (OR= 2,32; 95% IC= 1,17–4,59), hipertrigliceridemia (OR= 2,09; 95% IC= 1,10–4,33) e angioplastia coronariana (OR= 6,82; 95% IC= 1,44–32,18). Os dados sugerem que o antecedente de irregularidade menstrual, indicativo da ocorrência da síndrome dos ovários policísticos na idade reprodutiva, pode estar relacionado com aumento do risco para doenças CV na pós-menopausa __________________________________________________ABSTRACT Menstrual Cycle Irregularity as a Marker of Cardiovascular Risk Factors at Postmenopausal Years.To evaluate the association between cardiovascular risk factors (CVRF)during postmenopausal years and previous menstrual irregularity during reproductive years, we performed a case-control study in 414 postmenopausal women (mean age 60.4 ± 5.5 years; BMI 25.3 ± 4.7 kg/m2). The variables assessed were: menstrual cycle characteristics at age 20–35y (independent) and records of arterial hypertension, dyslipidemia, diabetes mellitus, and coronary heart disease (dependent). Statistical analysis used the chi-square test and logistic regression, adjusting for potential confounders for cardiovascular risk, with significance set at 5%. Women reporting previous menstrual irregularity were associated with increased risk for some CVRF [adjusted odds ratio (OR) 2.14; CI-95%= 1.02–4.48], when compared with those reporting regular menstrual cycles. Stratified analysis demonstrated significant associations of previous menstrual irregularity with: arterial hypertension [OR= 2.74; CI-95%= 1.39–5.41), hypercholesterolemia (OR= 2.32; CI-95%= 1.17–4.59), hypertriglyceridemia (OR= 2.09; CI-95%=1.10–4.33), and coronary angioplasty (OR= 6.82; CI-95%= 1.44–32.18). These data suggest that a prior history of menstrual irregularity, as indicative of polycystic ovary syndrome, may be related to increased risk for CVD during postmenopausal years

Relevância:

100.00% 100.00%

Publicador:

Resumo:

FERNANDES, Marcos Henrique; ROCHA, Vera Maria da; RONCALLI, Angelo Giuseppe. Fatores Associados à Prevalência de Sintomas Osteomusculares em Professores. Revista de salud pública, v. 11, n. 2, p. 256-267, 2009.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Objetivo: Investigar o impacto da saúde bucal em relação à qualidade de vida de adolescentes escolares, associando-o às condições sociodemográficas. Métodos: Estudo de campo transversal e quantitativo desenvolvido em 2012, no município de Sumé-PB, com 184 adolescentes na faixa etária de 15 a 19 anos. Para avaliar o impacto, aplicou-se o questionário Oral Health Impact Profile (OHIP-14) aos participantes, enquanto para a obtenção dos dados referentes às condições sociodemográficas, os pais ou responsáveis responderam a um segundo questionário. Utilizou-se o teste Qui-quadrado para associar o impacto da saúde bucal sobre a qualidade de vida e as variáveis sociodemográficas pesquisadas, sendo considerados significativos com p<0,05. Resultados: Em geral, o impacto foi considerado fraco em 167 pesquisados (90,8%). “Dor física” foi a dimensão na qualidade de vida mais afetada pelas questões bucais entre aquelas que resultaram em impacto médio (22,8%; n=42). Apenas as variáveis “Situação do imóvel” e “Acomodação” associaram-se ao impacto geral (p<0,05). Os reduzidos percentuais de impacto geral forte (1,1%; n=2) relacionaram-se aos adolescentes cujas mães só estudaram até o ensino fundamental, ou às famílias que vivem com um salário mínimo ou menos (1,1%). Conclusão: Observou-se que as condições de saúde bucal apresentaram um impacto negativo fraco na qualidade de vida dos adolescentes investigados. As análises das condições sociodemográficas dos indivíduos relacionadas ao impacto geral da qualidade de vida relacionada à saúde oral associaram-se as variáveis “Situação do imóvel” e “Acomodação”.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Portugal’s Northeast production of sheep and goats are based on the exploitation of landscape by-products such as spontaneous native vegetation and agriculture leftovers. Shepherds tend the flocks throughout grazing itineraries every day, crossing a mosaic of patches of varied land uses. During the journey, the shepherd acts together with the sheep and goats to select each patch in creating an ordered sequence of land uses. The focus of the research is on the land-use composition of the grazing itineraries; determinate how they depend on the patterns of the landscape mosaic. It is utilized a data set of 26 monthly herd’s itineraries, 13 of sheep and 13 of goats, to investigate the relationship of the land uses crossed by the flocks and the land uses of the landscape, evaluating the land-use preferences and selectivity of the sheep and goats. It is utilized the divergences in the time spent and distance travelled by the herds and the area of the land uses in the landscape, the chi-square test to relate the preferred land used and the season, and the discriminate analysis to distinguish the preferences and the selectivity of the herd of sheep and the herd of goats. The herds of the sheep and the goats presented different land-use preferences over the seasons and the discriminant analysis shows that they have different landscape preferences. The herd of sheep has the highest selectivity indexes for the annual irrigated crops, the agricultural complex systems and the agroforestry land uses. The highest selectivity indexes for the herd of goats were found for the deciduous forest, the agriculture with natural and semi-natural spaces and the shrublands land uses. It was concluded that the landscape management for sheep and goats herding has to be different: the agricultural land uses are essential to the flocks of sheep and the forest land uses are decisive to the flocks of goats.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

El presente artículo explora el uso de la WebQuest como metodología del Aprendizaje Basado en Proyectos Colaborativos en la formación de estudiantes de educación superior de la Escuela de Ingeniería Mecánica de la Escuela Superior Politécnica de Chimborazo (ESPOCH). Con esta finalidad se diseñó la WebQuest para ser aplicada con estudiantes entre 18 y 22 años en la asignatura de Programación. La investigación fue de tipo cognitivo-constructivista, descriptiva, de campo, transversal, aplicada, de ciencias básicas y bajo el paradigma científico, enmarcada bajo políticas y lineamientos del Plan Nacional del Buen Vivir 2013-2017. Mediante la utilización de herramientas colaborativas Google Drive y Google Sites, el test CHAEA para estilos de aprendizaje, herramientas ofimáticas y software especializado determinando así su incidencia en el aprendizaje significativo de los 54 estudiantes tomados como muestra. Se aplicaron dos técnicas estadísticas: t-Student para comprobar el rendimiento académico, comportamiento y estilos de aprendizaje. Con 5% de error y un punto crítico de 2,055 a dos colas, se obtuvieron valores de: 4,382, 2,434 y 3,701 respectivamente. La técnica Chi-cuadrado se aplicó para comprobar las habilidades del siglo XXI, con un punto crítico de 40,1, se generó el valor calculado de 119,84, demostrando que la metodología WebQuest favorece la generación de aprendizajes significativos dentro y fuera del aula de clase.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This study aimed to analyze the leadership style adopted by managers of nongovernmental organizations in the metropolitan region of Belem on the theory of Hersey and Blanchard. This theory is called situational leadership ranks E1, E2, E3, E4 and the styles of leadership and maturity in parallel classes M1, M2, M3 and M4. This study examined the relationship of leadership styles with the maturity of work, identified the relationship of leadership styles as related to psychological maturity and job maturity and psychological maturity. The main objectives were to analyze and relate leadership styles with the maturity of the leaders and understand the phenomenon of leadership from the self-perception of those who lead the organizations studied. To achieve the objectives we used a questionnaire already validated the theory of situational leadership and applied in 320 non-governmental organizations in the metropolitan region of Belem The methodology was quantitative, descriptive and exploratory. The analysis was by descriptive statistics and inferential statistics for univariate and bivariate form, applying the chi-square, the V Crammer and Spearman correlation. The data analysis shows safety, attested to the frequencies, and average margin of error and after application of the tests it was found that a relationship between the leadership style of work with the maturity and psychological maturity. The managers of nongovernmental organizations practicing various styles of leadership and focus on the quadrant of high maturity. It was diagnosed when the manager uses only one style of leadership was the predominance of E3 "share or support", which represents 24% of the sample. As uses two styles of leadership is the predominance of E3 and E2, which represents 76%. So the managers of nongovernmental organizations in the metropolitan region of Belem, practicing a style of leadership support, sharing ideas for decision making using a democratic style

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background: Cystic fibrosis (CF), a life-limiting autosomal recessive disorder, is considered a monogenic disease that is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. According to several studies, mutation analysis of the cystic fibrosis transmembrane conductance regulator (CFTR) gene alone is insufficient to predict the phenotypic manifestations observed in cystic fibrosis (CF) patients. In addition, some patients with a milder CF phenotype do not carry any pathogenic mutation. Tumor Necrosis Factor-alpha (TNF-α) contributes to the pathophysiology of CF by causing cachexia. There is a reverse association between TNF-α concentration in patient's sputum and their pulmonary function. Objectives: To assess the effect of non-CFTR genes on the clinical phenotype of CF, two polymorphic sites (-1031T/C and -308G/A) of the TNF-α gene, as a modifier, were studied. Patients and Methods: Focusing on the lung and gastrointestinal involvement as well as the poor growth, we first investigated the role of TNF-α gene in the clinical manifestation of CF. Furthermore, based on the hypothesis that the cumulative effect of specific alleles of multiple CF modifier genes, such as TNF-α, may create the final phenotype, we also investigated the potential role of TNF-α in non-classic CF patients without a known pathogenic mutation. In all, 80 CF patients and 157 healthy control subjects of Azeri Turkish ethnicity were studied by the PCR–RFLP method. The chi-square test with Yates' correction and Fisher's exact test were used for statistical analysis. Results: The allele and genotype distribution of the investigated polymorphisms, and their associated haplotypes were similar in all groups. Conclusions: There was no evidence that supported the association of TNF-α gene polymorphisms with non-classic CF disease or the clinical presentation of classic CF.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background: Preterm labor, which defines as live-birth delivery before 37 weeks of gestation is a main determinant of neonatal morbidity and mortality around the world. Objective: The aim of this study was to determine the prevalence of preterm labor in Iran by a meta-analysis study, to be as a final measure for policy makers in this field. Materials and Methods: In this meta-analysis, the databases of Thomson database (Web of Knowledge), PubMed/Medline, Science Direct, Scopus, Google Scholar, Iranmedex, Scientific Information Database (SID), Magiran, and Medlib were searched for articles in English and Persian language published between 1995 and 2014. Among the studies with regard to the inclusion and exclusion criteria, 14 studies (out of 1370 publications) were selected. Data were analyzed by using Stata software version 11. The heterogeneity of reported prevalence among studies was evaluated by the Chi-square based Q test and I2 statistics. Results: The results of Chi-square based on Q test and I2 statistics revealed severe heterogeneity (Q=2505.12, p-value < 0.001 and I2= 99.5%) and consequently, the random effect model was used for the meta-analysis. Based on the random effect model, the overall estimated prevalence of preterm in Iran was 9.2% (95% CI: 7.6 – 10.7). Conclusion: Present study summarized the results of previous studies and provided a comprehensive view about the preterm delivery in Iran. In order to achieve a more desirable level and its reduction in the coming years, identifying affecting factor and interventional and preventive actions seem necessary.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Introducción: Las patologías del hombro suelen ser una de las causas de mayor solicitud de consulta en el ámbito laboral, con generación de incapacidad y pérdidas económicas, tanto para el afectado como para la empresa e incluso, la Entidad Promotora de Salud responsable de la atención y tratamiento. Entre las patologías de hombro más frecuentes se hallan el síndrome del manguito rotador, bursitis del hombro, síndrome de abducción dolorosa del hombro, tendinitis del bíceps, traumatismos del tendón del manguito rotador y tendinitis calcificante del hombro. Objetivo: Determinar y caracterizar las patologías del hombro de origen común y laboral, las prestaciones asistenciales y económicas que de estas se deriva en una EPS durante el periodo 2012 a 2014 en la ciudad de Bogotá. Metodología: Se realizó un estudio de corte transversal con datos secundarios procedentes de 657 afiliados del Régimen Contributivo en una EPS de la ciudad de Bogotá, con información de las patologías del hombro registradas de origen común y laboral, durante el periodo de 2012 a 2014. Las variables incluidas fueron las sociodemográficas, ocupacionales y clínicas. Se describieron las variables cualitativas en términos de proporción y las variables cuantitativas a través de medidas de tendencia central (medias/ medianas) y dispersión (rangos, desviación estándar, cuartiles). Para evaluar la asociación entre variables se utilizó la prueba de Chi cuadrado de Pearson usando nivel de significación α de 0,05. Resultados: Del total de afiliados se encontró que el 27,3% de las patologías fueron de origen laboral y el resto de origen común, predominando el género femenino (76.9%); el estado civil casado (34,4%), la escolaridad secundaria (60,4%). Un alto porcentaje de los pacientes se han desempeñado en la industria manufacturera (51%) y el diagnóstico más frecuente fue el síndrome de manguito rotatorio (89,2%). Al revisar los factores asociados con el origen de la patología en la calificación de estas, se encontró asociación con la edad (p = 0,000), la escolaridad (p = 0,013), la actividad económica (p = 0,0000), el factor ocupacional ergonómico (p = 0,0000) y con los diagnósticos de patologías del hombro (p = 0,025). Los días de incapacidad por las patologías del hombro reportaron una mediana de 111 días con rango de 0 a 1925 días. El tiempo de exposición al factor de riesgo ocupacional presento un rango de 6 a 470 meses, los costos por las patologías del hombro generadas correspondieron a un rango de $4000 a $68894438, con una mediana de $2287304. Es transcendental diagnosticar a tiempo e instaurar medidas terapéuticas, que permitan mejorar la sintomatología que ocasionan las patologías del hombro y la alteración en la funcionalidad del mismo, minimizando así los costos y días de incapacidad que a esto conlleva.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Children and adolescents are now using online communication to form and/or maintain relationships with strangers and/or friends. Relationships in real life are important for children and adolescents in identity formation and general development. However, social relationships can be difficult for those who experience feelings of loneliness and social anxiety. The current study aimed to replicate and extend research conducted by Valkenburg and Peter (2007b), by investigating differences in online communication patterns between children and adolescents with and without selfreported loneliness and social anxiety. Six hundred and twenty-six students aged 10-16 years completed a questionnaire survey about the amount of time they engaged in online communication, the topics they discussed, who they communicated with, and their purposes of online communication. Following Valkenburg and Peter (2007b), loneliness was measured with a shortened version of the UCLA Loneliness Scale (Version 3) developed by Russell (1996), whereas social anxiety was assessed with a sub-scale of the Social Anxiety Scale for Adolescents (La Greca & Lopez, 1998). The sample was divided into four groups of children and adolescents: 220 were “non-socially anxious and non-lonely”, 139 were “socially anxious but not lonely”, 107 were “lonely but not socially anxious”, and 159 were “lonely and socially anxious”. A one-way ANOVA and chi-square tests were conducted to evaluate the aforementioned differences between these groups. The results indicated that children and adolescents who reported being lonely used online communication differently from those who did not report being lonely. Essentially, the former communicated online more frequently about personal things and intimate topics, but also to compensate for their weak social skills and to meet new people. Further analyses on gender differences within lonely children and adolescents revealed that boys and girls communicated online more frequently with different partners. It was concluded that for these vulnerable individuals online communication may fulfil needs of self-disclosure, identity exploration, and social interactions. However, future longitudinal studies combining a quantitative with a qualitative approach would better address the relationship between Internet use and psychosocial well-being. The findings also suggested the need for further exploration of how such troubled children and adolescents can use the Internet beneficially.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background/Rationale Guided by the need-driven dementia-compromised behavior (NDB) model, this study examined influences of the physical environment on wandering behavior. Methods Using a descriptive, cross-sectional design, 122 wanderers from 28 long-term care (LTC) facilities were videotaped 10 to 12 times; data on wandering, light, sound, temperature and humidity levels, location, ambiance, and crowding were obtained. Associations between environmental variables and wandering were evaluated with chi-square and t tests; the model was evaluated using logistic regression. Results In all, 80% of wandering occurred in the resident’s own room, dayrooms, hallways, or dining rooms. When observed in other residents’ rooms, hallways, shower/baths, or off-unit locations, wanderers were likely (60%-92% of observations) to wander. The data were a good fit to the model overall (LR [logistic regression] χ2 (5) = 50.38, P < .0001) and by wandering type. Conclusions Location, light, sound, proximity of others, and ambiance are associated with wandering and may serve to inform environmental designs and care practices.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Statistical modeling of traffic crashes has been of interest to researchers for decades. Over the most recent decade many crash models have accounted for extra-variation in crash counts—variation over and above that accounted for by the Poisson density. The extra-variation – or dispersion – is theorized to capture unaccounted for variation in crashes across sites. The majority of studies have assumed fixed dispersion parameters in over-dispersed crash models—tantamount to assuming that unaccounted for variation is proportional to the expected crash count. Miaou and Lord [Miaou, S.P., Lord, D., 2003. Modeling traffic crash-flow relationships for intersections: dispersion parameter, functional form, and Bayes versus empirical Bayes methods. Transport. Res. Rec. 1840, 31–40] challenged the fixed dispersion parameter assumption, and examined various dispersion parameter relationships when modeling urban signalized intersection accidents in Toronto. They suggested that further work is needed to determine the appropriateness of the findings for rural as well as other intersection types, to corroborate their findings, and to explore alternative dispersion functions. This study builds upon the work of Miaou and Lord, with exploration of additional dispersion functions, the use of an independent data set, and presents an opportunity to corroborate their findings. Data from Georgia are used in this study. A Bayesian modeling approach with non-informative priors is adopted, using sampling-based estimation via Markov Chain Monte Carlo (MCMC) and the Gibbs sampler. A total of eight model specifications were developed; four of them employed traffic flows as explanatory factors in mean structure while the remainder of them included geometric factors in addition to major and minor road traffic flows. The models were compared and contrasted using the significance of coefficients, standard deviance, chi-square goodness-of-fit, and deviance information criteria (DIC) statistics. The findings indicate that the modeling of the dispersion parameter, which essentially explains the extra-variance structure, depends greatly on how the mean structure is modeled. In the presence of a well-defined mean function, the extra-variance structure generally becomes insignificant, i.e. the variance structure is a simple function of the mean. It appears that extra-variation is a function of covariates when the mean structure (expected crash count) is poorly specified and suffers from omitted variables. In contrast, when sufficient explanatory variables are used to model the mean (expected crash count), extra-Poisson variation is not significantly related to these variables. If these results are generalizable, they suggest that model specification may be improved by testing extra-variation functions for significance. They also suggest that known influences of expected crash counts are likely to be different than factors that might help to explain unaccounted for variation in crashes across sites