Dependent Variable (dependent + variable)

Distribution by Scientific Domains
Distribution within Medical Sciences

Terms modified by Dependent Variable

  • dependent variable models

  • Selected Abstracts


    What is the Dependent Variable in Corporate Governance Research?

    CORPORATE GOVERNANCE, Issue 5 2008
    William Judge
    No abstract is available for this article. [source]


    Panel Data Discrete Choice Models with Lagged Dependent Variables

    ECONOMETRICA, Issue 4 2000
    Bo E. Honoré
    In this paper, we consider identification and estimation in panel data discrete choice models when the explanatory variable set includes strictly exogenous variables, lags of the endogenous dependent variable as well as unobservable individual-specific effects. For the binary logit model with the dependent variable lagged only once, Chamberlain (1993) gave conditions under which the model is not identified. We present a stronger set of conditions under which the parameters of the model are identified. The identification result suggests estimators of the model, and we show that these are consistent and asymptotically normal, although their rate of convergence is slower than the inverse of the square root of the sample size. We also consider identification in the semiparametric case where the logit assumption is relaxed. We propose an estimator in the spirit of the conditional maximum score estimator (Manski (1987)) and we show that it is consistent. In addition, we discuss an extension of the identification result to multinomial discrete choice models, and to the case where the dependent variable is lagged twice. Finally, we present some Monte Carlo evidence on the small sample performance of the proposed estimators for the binary response model. [source]


    GENETIC STUDY: Polymorphisms of the dopamine D4 receptor gene (DRD4 VNTR) and cannabinoid CB1 receptor gene (CNR1) are not strongly related to cue-reactivity after alcohol exposure

    ADDICTION BIOLOGY, Issue 2 2007
    Esther Van Den Wildenberg
    ABSTRACT Polymorphisms in the D4 dopamine receptor gene (DRD4) and the CB1 cannabinoid receptor gene (CNR1) have been associated with a differential response to alcohol after consumption. The goal of the present study was to investigate whether heavy drinkers with these polymorphisms would respond with enhanced cue-reactivity after alcohol exposure. Eighty-eight male heavy drinkers were genotyped for the DRD4 variable number of tandem repeats (VNTR) [either DRD4 long (L) or short (S)] and the CNR1 rs2023239 polymorphism (either CT/CC or TT). Participants were exposed to water and beer in 3-minute trials. Dependent variables of main interest were subjective craving for alcohol, subjective arousal and salivary reactivity. Overall, no strong evidence was found for stronger cue-reactivity (= outcome difference between beer and water trial) in the DRD4 L and CNR1 C allele groups. The DRD4 VNTR polymorphism tended to moderate salivary reactivity such that DRD4 L participants showed a larger beverage effect than the DRD4 S participants. Unexpectedly, the DRD4 L participants reported, on average, less craving for alcohol and more subjective arousal during cue exposure, compared with the DRD4 S participants. As weekly alcohol consumption increased, the CNR1 C allele group tended to report more craving for alcohol during the alcohol exposure than the T allele group. The DRD4 and CNR1 polymorphisms do not appear to strongly moderate cue-reactivity after alcohol cue exposure, in male heavy drinkers. [source]


    Nurse absenteeism and workload: negative effect on restraint use, incident reports and mortality

    JOURNAL OF ADVANCED NURSING, Issue 6 2007
    Lynn Unruh
    Abstract Title.,Nurse absenteeism and workload: negative effect on restraint use, incident reports and mortality Aim., This paper is a report of a study to assess the impact of nurse absenteeism on the quality of patient care. Background., Nurse absenteeism is a growing management concern. It can contribute to understaffed units, staffing instability, and other factors that could have a negative impact on patient care. The impacts of absenteeism on the quality of nursing care have rarely been studied. Method., Retrospective monthly data from incident reports and staffing records in six inpatient units for 2004 were analysed. Dependent variables were the numbers of restraints, alternatives to restraints, incident reports, deaths, and length of stay. Explanatory variables were nurse absenteeism hours, patient days per nursing staff, and interaction between these variables. Controls were patient acuity and unit characteristics. Fixed effects regressions were analysed as regular or negative binomial models. Findings., Neither high Registered Nurse absenteeism nor high patient load was related to restraint use when taken separately. However, high Registered Nurse absenteeism was related to restraint use when patient load was high. Registered Nurse absenteeism was related to a lower use of alternatives to restraints. Incident reports were increased by high patient load, but not absenteeism, or absenteeism given patient load. When both patient load and absenteeism were high, deaths were higher also. Conclusion., Absenteeism alone may not be a strong factor in lowering quality, but the combination of high Registered Nurse absenteeism and high patient load could be a factor. Staffing and absenteeism may be part of a vicious cycle in which low staffing contributes to unit absenteeism, which contributes to low staffing, and so on. [source]


    Social Presence and Children: Praise, Intrinsic Motivation, and Learning With Computers

    JOURNAL OF COMMUNICATION, Issue 1 2004
    Cheryl Campanella Bracken
    The computers are social actors (CASA) paradigm asserts that human computer users interact socially with computers, and the paradigm has provided extensive evidence that this is the case for adults. This experiment examined whether or not children have similar reactions to computers by comparing children's predictable responses to praise from a teacher to their responses to praise from a computer. Eight- to 10-year-old participants (N= 42) received either praise or neutral feedback from a computer. Independent variables were the feedback (praise or neutral), and participants' age and gender. Dependent variables measured via a paper-and-pencil questionnaire were learning (recall and recognition memory), perceived ability, and intrinsic motivation. Results provide evidence that children do have social responses to computers and that such social responses can lead to increases in learning (recall and recognition) in young children. [source]


    The Impact of HIV on Oral Health and Subsequent Use of Dental Services

    JOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 2 2003
    Aram Dobalian PhD
    Abstract Objective: This study examined differences in health and access to dental services among a nationally representative sample of patients with HIV using Andersen's Behavioral Model of Health Services Use. Methods: This investigation is a longitudinal study that used structural equation modeling to analyze data from the HIV Cost and Services Utilization Study, a probability sample of 2,864 adults under treatment for HIV infection. Key predisposing variables included sex, drug use, race/ethnicity, education, and age. Enabling factors included income, insurance, and regular source of care. Need factors included mental, physical, and oral health. Dependent variables included whether a respondent utilized dental services and number of visits. Results: More education, dental insurance, usual source of dental care, and poor oral health predicted a higher probability of having a dental visit. African Americans, Hispanics, those exposed to HIV through drug use or heterosexual contact, and those in poor physical health were less likely to have a dental visit. Of those who visited dental professionals, older persons, those with dental insurance, and those in worse oral health had more visits. African Americans and persons in poor mental health had fewer visits. Conclusions: Persons with more HIV-related symptoms and a diagnosis of AIDS have a greater need for dental care than those with fewer symptoms and without AIDS, but more pressing needs for physical and mental health services limit their access to dental services. Providers should better attend to the oral health needs of persons with HIV who are in poor physical and mental health. [source]


    Plant traits as predictors of woody species dominance in climax forest communities

    JOURNAL OF VEGETATION SCIENCE, Issue 3 2001
    Fumito Koike
    Satake et al. (1989) Abstract. The dominance of a given tree or shrub species in a particular forest community may be determined by many ecological traits of the target species, as well as those of the surrounding species as its potential competitors. The present study was conducted to evaluate the possibility of predicting community status (species composition and dominance) on the basis of traits of local flora using statistical methods, and to visualize the mathematical function which determines species dominance. A general linear model and logistic regression were used for the statistical analysis. Dependent variables were designated as dominance and presence/absence of species in climax forest, with independent variables as vegetative and reproductive traits. Subalpine, cool-temperate, warm-temperate and subtropical climax rain forests in East Asia were studied. Quantitative prediction of climax community status could readily be made based on easily measured traits of local flora. Species composition and 74.6% of the total variance of species dominance were predicted based on two traits; maximum height and shade tolerance. Through application of this method, the capacity of an alien species to invade a climax forest community could possibly be predicted prior to introduction of the alien species. [source]


    The phenomenology of exception times: Qualitative differences between problem-focussed and solution-focussed interventions

    APPLIED COGNITIVE PSYCHOLOGY, Issue 4 2010
    Thomas Wehr
    Solution-focussed brief therapy (SFBT) is a prominent psychotherapeutic approach that deals with a positive focus and promises brief interventions. In two experiments, a solution-focussed technique was compared with a problem-focussed intervention. By means of a structured questionnaire, subjects were encouraged to think about a standard (Experiment 1) or a facultative topic (Experiment 2). Subsequently, they generated either one or five exceptions or exemplary problem episodes. Dependent variables were confident in coping with the problem, ease of retrieval, psychic comfort and several phenomenological properties of the autobiographical memory. A solution-oriented intervention increased self-confidence and established a positive mood. Exception times had a more positive tone and were generally more easily retrieved than problem episodes. The study confirms the claims of the SFBT for empowerment and rapid reduction of current suffering. Copyright © 2009 John Wiley & Sons, Ltd. [source]


    REASSESSING NONLINEARITY IN THE URBAN DISADVANTAGE/VIOLENT CRIME RELATIONSHIP: AN EXAMPLE OF METHODOLOGICAL BIAS FROM LOG TRANSFORMATION,

    CRIMINOLOGY, Issue 4 2003
    LANCE HANNON
    Sociologists and criminologists have become increasingly concerned with nonlinear relationships and interaction effects. For example, some recent studies suggest that the positive relationship between neighborhood disadvantage and violent crime is nonlinear with an accelerating slope, whereas other research indicates a nonlinear decelerating slope. The present paper considers the possibility that this inconsistency in findings is partially caused by lack of attention to an important methodological concern. Specifically, we argue that researchers have not been sensitive to the ways in which logarithmic transformation of the dependent variable can bias tests for nonlinearity and statistical interaction. We illustrate this point using demographic and violent crime data for urban neighborhoods, and we propose an alternative procedure to log transformation that involves the use of weighted least-squares regression, heteroscedasticity consistent standard errors, and diagnostics for influential observations. [source]


    Student Hits in an Internet-Supported Course: How Can Instructors Use Them and What Do They Mean?

    DECISION SCIENCES JOURNAL OF INNOVATIVE EDUCATION, Issue 2 2003
    Andrew, Ellen Baugher Varanelli Weisbord
    ABSTRACT The world of education is changing as Web-based technology and courseware are increasingly used for delivery of course material. In this environment, instructors may need new measures for determining student involvement, and ultimately student performance. This study examines whether hits to a Web site have any value for predicting student performance in a traditional course supported by Web activities. Total Hits at the end of the semester was used as one measure. Hit Consistency, determined by assigning a 0 when no hits occurred between class meetings and by assigning a 1 when one or more hits occurred between class meetings, was another. Hit Consistency was significantly correlated with course average (r= .37, p < .001) for 108 students in two course sections. Hit Consistency started to show a significant relationship with course average by the third week (or class). Total Hits was not found to significantly correlate with course average (r= .08, p > .05) at the end of the semester or during any week. These results suggest that students who consistently access a Web site will perform better than those who do not. When Hit Consistency and Total Hits were entered as independent variables into a stepwise regression with course average as the dependent variable, the model was enhanced by the addition of Total Hits after Hit Consistency was entered (R= .43, p < .001). Hierarchical regression analysis in which cumulative grade point average was entered as the first controlling variable suggested that online access may go beyond the predictive value of achievement alone for predicting course performance with Hit Consistency appearing to be the dominant causal variable. [source]


    Insulin resistance is not coupled with defective insulin secretion in primary hyperparathyroidism

    DIABETIC MEDICINE, Issue 10 2009
    F. Tassone
    Abstract Aims, An increased frequency of both impaired glucose tolerance and Type 2 diabetes mellitus (DM) has been reported in primary hyperparathyroidism (pHPT), thus we sought to investigate insulin sensitivity and insulin secretion in a large series of pHPT patients. Subjects and methods, One hundred and twenty-two consecutive pHPT patients without known DM were investigated [age (mean ± sd) 59.3 ± 13.6 years, body mass index (BMI) 25.7 ± 4.2 kg/m2; serum calcium 2.8 ± 0.25 mmol/l; PTH 203.2 ± 145.4 ng/l]. Sixty-one control subjects were matched, according to the degree of glucose tolerance, in a 2 : 1 patient:control ratio. Fasting- and oral glucose tolerance test-derived estimates of insulin sensitivity and secretion were determined by means of the quantitative insulin sensitivity check index (QUICKI) and the insulin sensitivity index (ISI) composite. Results, Both the QUICKI and ISI composite were lower in pHPT patients than control subjects (P < 0.03 and P < 0.05, respectively) after adjusting for age, systolic blood pressure and BMI. Conversely, all insulin secretion estimates were significantly increased in pHPT patients than in control subjects (P < 0.04 and P < 0.03, respectively) and after adjusting for age, systolic blood pressure and BMI. Log serum calcium levels were negatively associated with the QUICKI and log ISI composite (R = ,0.30, P = 0.001; R = ,0.23, P = 0.020, respectively) in pHPT patients. Serum calcium levels significantly and independently contributed to impaired insulin sensitivity in multivariate analysis (QUICKI as dependent variable: , = ,0.31, P = 0.004, R2 = 0.15; log ISI composite as dependent variable: , = ,0.29, P = 0.005, R2 = 0.16). Conclusions, Our study confirms a reduction in both basal and stimulated insulin sensitivity in primary hyperparathyroidism, in spite of increased insulin secretion. Moreover, our data show for the first time a significant relationship between hypercalcaemia and insulin sensitivity in this condition. [source]


    Can solving of wordchains be explained by phonological skills alone?

    DYSLEXIA, Issue 1 2010
    Arve E. Asbjørnsen
    Abstract The present study focussed on the determinants for effective solving of the Wordchains Test (WCT) in a normative sample of Norwegian junior high-school students. Forty voluntary participants from a rural school district in Western Norway completed the WCT along with tests of general intellectual capacity, single word and non-word reading, auditory working memory, and visual scanning. All measures correlated significantly with each other except for general non-verbal abilities were not correlated with visual scanning. A stepwise multiple regression analysis, using the WCT as the dependent variable, yielded a model that included single word reading, letter recognition, and working memory as independent variables. This model accounted for 75% of the variance in WCT performance. This finding suggests that phonological skills only have an indirect influence on WCT performance. Thus, the core deficit in dyslexia, i.e. impaired phonological skills, may be related to the development of word recognition skills, but have no direct effect on the WCT performance in a normative sample. Copyright © 2009 John Wiley & Sons, Ltd. [source]


    Cross Section and Panel Data Estimators for Nonseparable Models with Endogenous Regressors

    ECONOMETRICA, Issue 4 2005
    Joseph G. Altonji
    We propose two new methods for estimating models with nonseparable errors and endogenous regressors. The first method estimates a local average response. One estimates the response of the conditional mean of the dependent variable to a change in the explanatory variable while conditioning on an external variable and then undoes the conditioning. The second method estimates the nonseparable function and the joint distribution of the observable and unobservable explanatory variables. An external variable is used to impose an equality restriction, at two points of support, on the conditional distribution of the unobservable random term given the regressor and the external variable. Our methods apply to cross sections, but our lead examples involve panel data cases in which the choice of the external variable is guided by the assumption that the distribution of the unobservable variables is exchangeable in the values of the endogenous variable for members of a group. [source]


    Panel Data Discrete Choice Models with Lagged Dependent Variables

    ECONOMETRICA, Issue 4 2000
    Bo E. Honoré
    In this paper, we consider identification and estimation in panel data discrete choice models when the explanatory variable set includes strictly exogenous variables, lags of the endogenous dependent variable as well as unobservable individual-specific effects. For the binary logit model with the dependent variable lagged only once, Chamberlain (1993) gave conditions under which the model is not identified. We present a stronger set of conditions under which the parameters of the model are identified. The identification result suggests estimators of the model, and we show that these are consistent and asymptotically normal, although their rate of convergence is slower than the inverse of the square root of the sample size. We also consider identification in the semiparametric case where the logit assumption is relaxed. We propose an estimator in the spirit of the conditional maximum score estimator (Manski (1987)) and we show that it is consistent. In addition, we discuss an extension of the identification result to multinomial discrete choice models, and to the case where the dependent variable is lagged twice. Finally, we present some Monte Carlo evidence on the small sample performance of the proposed estimators for the binary response model. [source]


    Modeling Passing Rates on a Computer-Based Medical Licensing Examination: An Application of Survival Data Analysis

    EDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 3 2004
    André F. de Champlain
    The purpose of this article was to model United States Medical Licensing Examination (USMLE) Step 2 passing rates using the Cox Proportional Hazards Model, best known for its application in analyzing clinical trial data. The number of months it took to pass the computer-based Step 2 examination was treated as the dependent variable in the model. Covariates in the model were: (a) medical school location (U.S. and Canadian or other), (b) primary language (English or other), and (c) gender. Preliminary findings indicate that examinees were nearly 2.7 times more likely to experience the event (pass Step 2) if they were U.S. or Canadian trained. Examinees with English as their primary language were 2.1 times more likely to pass Step 2, but gender had little impact. These findings are discussed more fully in light of past research and broader potential applications of survival analysis in educational measurement. [source]


    Separated by a Common Language?

    ENTREPRENEURSHIP THEORY AND PRACTICE, Issue 2 2008
    Entrepreneurship Research Across the Atlantic
    While recent inventories and assessments of the entrepreneurship field examine the focus, purpose, and methods, one area receiving less attention is the outcome or dependent variable. The outcome variable is of critical importance in scholarship, as it is a leading indicator of the cumulative nature of the scholarship in our field. This paper reviews 389 articles published over the past 3 years in four top entrepreneurship journals; two published in the United States and two published in Europe. It classifies the scholarship by theoretical underpinnings, independent variables, dependent variables, and then looks at the variation in these by origin of the journal. Results indicate that entrepreneurship researchers are using a wide variety of dependent variables, that the most popular unit of analysis is the firm, and that performance, broadly defined, is the most popular dependent variable. Implications for future research are discussed. [source]


    Cytogenetic status in newborns and their parents in Madrid: The BioMadrid study

    ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 4 2010
    Virginia Lope
    Abstract Monitoring cytogenetic damage is frequently used to assess population exposure to environmental mutagens. The cytokinesis-block micronucleus assay is one of the most widely used methods employed in these studies. In the present study we used this assay to assess the baseline frequency of micronuclei in a healthy population of father-pregnant woman-newborn trios drawn from two Madrid areas. We also investigated the association between micronucleus frequency and specific socioeconomic, environmental, and demographic factors collected by questionnaire. Mercury, arsenic, lead, and cadmium blood levels were measured by atomic absorption spectrometry. The association between micronucleated cell frequency and the variables collected by questionnaire, as well as, the risk associated with the presence of elevated levels of metals in blood, was estimated using Poisson models, taking the number of micronucleated cells in 1,000 binucleated cells (MNBCs) as the dependent variable. Separate analyses were conducted for the 110 newborns, 136 pregnant women, and 134 fathers in whom micronuclei could be assessed. The mean number of micronucleated cells per 1,000 binucleated cells was 3.9, 6.5, and 6.1 respectively. Our results show a statistically significant correlation in MNBC frequency between fathers and mothers, and between parents and newborns. Elevated blood mercury levels in fathers were associated with significantly higher MNBC frequency, compared with fathers who had normal mercury levels (RR:1.21; 95%CI:1.02,1.43). This last result suggests the need to implement greater control over populations which, by reason of their occupation or life style, are among those most exposed to this metal. Environ. Mol. Mutagen., 2010. © 2009 Wiley-Liss, Inc. [source]


    Transition and sustainability: empirical analysis of environmental Kuznets curve for water pollution in 25 countries in Central and Eastern Europe and the Commonwealth of Independent States

    ENVIRONMENTAL POLICY AND GOVERNANCE, Issue 2 2009
    Sandra O. Archibald
    Abstract This paper examines the effects of political, structural and economic changes on environmental quality in 25 Central and East European countries (CEECs) and the countries of the Commonwealth of Independent States (CIS) using selected water pollution indicators and by testing the environmental Kuznets curve (EKC). Despite substantial research on the transition effects from centrally planned economies and totalitarian political systems to democracy and free market economies, the literature is limited with respect to the short- and long-term environmental impacts. Considering the institutional and structural changes in these economies, rising per capita income and increased trade and investment openness, these countries can be characterized as early, late and non-liberalizers with respect to the start and continuation of liberalization processes , a critical element of the systemic transformation in the CEECs. While trends in selected economic and social indicators (based on the OECD pressure,state,response framework) show that early liberalizers enjoyed positive gains relative to late liberalizers, the selected environmental indicators do not indicate consistent trends with regard to surface water quality. Among early and late liberalizers, nitrate, orthophosphate and ammonium concentrations decline and converge over time. Phosphorus concentrations initially dropped but then increased again for both groups of countries. Using the indicator of biological oxygen demand (BOD) as the dependent variable and a set of structural and economic measures as the independent variables, our econometric regression model provides some evidence for the EKC hypothesis and estimates the per capita income turning point for industrial BOD effluents to be approximately 3800,5000 USD. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment. [source]


    Analyzing wildfire threat counts using a negative binomial regression model

    ENVIRONMETRICS, Issue 6 2006
    J. A. Quintanilha
    Abstract The fire-monitoring program managed by the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis collected fire pixel counts from 1998 to 2002 and used them as a measure of wildfire threats for the Amazon region. The objective of the study was to identify the most relevant explanatory variables related to the frequency of fire pixel occurrence. The sample unit was the municipality, the dependent variable was a function of fire pixel counts, and the explanatory variables were related to land management, census, and agricultural data. A generalized longitudinal linear model was used. The most relevant explanatory variables were administrative limits, year, type of region, season, percentages of deforested area and male population, extent of unpaved road, and density of cattle. Approximately 95% of the standardized residuals resulting from fitting the model were in the interval [,2, +2]. Copyright © 2006 John Wiley & Sons, Ltd. [source]


    Alcohol consumption increases attractiveness ratings of opposite-sex faces: a possible third route to risky sex

    ADDICTION, Issue 8 2003
    Barry T. Jones
    ABSTRACT Aims, To measure the effect of moderate alcohol consumption on males' and females' attractiveness ratings of unfamiliar male and female faces. Participants Eighty undergraduate volunteers were used in each of three experiments. Design, Participants' ratings on a 1,7 scale was the dependent variable. A three-factor mixed design was used. For experiments 1 and 2: one within-factor, sex-of-face to be rated (male/female); two between-factors, sex-of-rater (male/female) and alcohol status of rater (0 UK units/1,6 UK units). For experiment 3, the two levels of sex-of-face were replaced by two levels of a non-face object. In experiment 1, the faces were rated for attractiveness; in experiment 2, the faces were rated for distinctiveness and in experiment 3, the non-face objects were rated for attractiveness. Setting, Quiet, prepared corners of bars and licensed eating areas on a civic university campus. Method, For each experiment, 118 full-colour photographic images were presented randomly on a laptop computer screen, each remaining until a rating response was made. Findings, There was a significant alcohol consumption enhancement effect only for attractiveness ratings of opposite-sex faces in experiment 1. This indicates that the opposite-sex enhancement effect is not due simply to alcohol consumption causing the use of higher points of ratings scales, in general. Conclusion, Since Agocha & Cooper have shown that the likelihood of intentions to engage in risky sex increases as the facial attractiveness of the potential sexual partner increases, through the opposite-sex enhancement effect we identify a new possible link between risky sex and alcohol consumption. [source]


    Contemporary issues and future directions for research into pathological gambling

    ADDICTION, Issue 8 2000
    Article first published online: 2 SEP 200
    The recent healthy increase in research into all aspects of gambling is noted. The dominant theme accounting for most of this research is the mental disorder model of pathological gambling and measures that have been derived from this conceptualization. It is suggested that an alternative approach focusing on the construct of choice or subjective control over gambling may be a research direction that will ensure that progress is maintained. In this paper a context for the discussion is provided by first identifying briefly fundamental conceptual and methodological issues associated with the mental disorder model. In particular it is argued that the heterogeneity of the diagnosis of pathological gambling makes the research task of assessing truly independent variables extremely difficult. Subsequently an illustrative schema is presented that demonstrates both the potential advantages and some of the complexities associated with the dependent variable of self-control over gambling behaviour. The main advantages are argued to be (a) the focus of research is narrowed to one potential cause of harmful impacts rather than the great diversity of impacts themselves, (b) prospective studies of regular gamblers in real gambling venues may be a key source of insight into the development of pathological gambling and (c) it promotes the development of theoretical links with the mainstream of the discipline of psychology. Despite the conceptual difficulties that may be associated with the variable of self-control, it is suggested that these may be overcome because contemporary research into the addictive behaviours has demonstrated considerable success in the definition and measurement of control and related themes such as craving, restraint and temptation. [source]


    Effects of an occlusal splint compared with cognitive-behavioral treatment on sleep bruxism activity

    EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2007
    Michelle A. Ommerborn
    The impact of an occlusal splint (OS) compared with cognitive-behavioral treatment (CBT) on the management of sleep bruxism (SB) has been poorly investigated. The aim of this study was to evaluate the efficacy of an OS with CBT in SB patients. Following a randomized assignment, the OS group consisted of 29, and the CBT group of 28, SB patients. The CBT comprised problem-solving, progressive muscle relaxation, nocturnal biofeedback, and training of recreation and enjoyment. The treatment took place over a period of 12 wk, and the OS group received an OS over the same time period. Both groups were examined pretreatment, post-treatment, and at 6 months of follow-up for SB activity, self-assessment of SB activity and associated symptoms, psychological impairment, and individual stress-coping strategies. The analyses demonstrated a significant reduction in SB activity, self-assessment of SB activity, and psychological impairment, as well as an increase of positive stress-coping strategies in both groups. However, the effects were small and no group-specific differences were seen in any dependent variable. This is an initial attempt to compare CBT and OS in SB patients, and the data collected substantiate the need for further controlled evaluations, using a three-group randomized design with repeated measures to verify treatment effects. [source]


    A multivariate analysis of the outcome of endodontic treatment

    EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2004
    Dag Ørstavik
    In the present study, multivariate analyses were performed on clinical and treatment variables that may influence the outcome of endodontic treatment. Data collected in a previous clinical-radiographic follow-up study were used. Of 810 treated, 675 roots in 498 teeth were followed for 6 months to 4 yr. Of these, 192 (the CAP group) had pre-existing, chronic apical periodontitis and 483 (the NAP group) had not. Root canal treatment followed a standard procedure with one of three sealers chosen at random. Demographic, clinical and radiographic variables were recorded at the start of, and during treatment. The periapical index (PAI) score was used to record the outcome of treatment, and applied in two different endpoint modes (END1 and END2) as the dependent variable for multivariate statistical analyses using logistic regression and the general model. The modes reflected increasing PAI scores (END1) and conventional success/failure assessment (END2). Dropouts were largely similar to the cases followed up. A total of 10 preoperative and peroperative variables were found to be significantly associated with treatment outcome by the multivariate analyses of either the total material or the NAP or CAP subgroups. Several of these were not significant in univariate analyses (e.g. the effect of sealer). Conventional success/failure analyses (END2) identified fewer of the influential variables and had low explanatory power, whereas PAI scores on an ordinal scale (END1) were most sensitive in identifying variables of influence on the treatment outcome. [source]


    MEASURING PROBABILISTIC REACTION NORMS FOR AGE AND SIZE AT MATURATION

    EVOLUTION, Issue 4 2002
    Mikko Heino
    Abstract We present a new probabilistic concept of reaction norms for age and size at maturation that is applicable when observations are carried out at discrete time intervals. This approach can also be used to estimate reaction norms for age and size at metamorphosis or at other ontogenetic transitions. Such estimations are critical for understanding phenotypic plasticity and life-history changes in variable environments, assessing genetic changes in the presence of phenotypic plasticity, and calibrating size- and age-structured population models. We show that previous approaches to this problem, based on regressing size against age at maturation, give results that are systematically biased when compared to the probabilistic reaction norms. The bias can be substantial and is likely to lead to qualitatively incorrect conclusions; it is caused by failing to account for the probabilistic nature of the maturation process. We explain why, instead, robust estimations of maturation reaction norms should be based on logistic regression or on other statistical models that treat the probability of maturing as a dependent variable. We demonstrate the utility of our approach with two examples. First, the analysis of data generated for a known reaction norm highlights some crucial limitations of previous approaches. Second, application to the northeast arctic cod (Gadus morhua) illustrates how our approach can be used to shed new light on existing real-world data. [source]


    A Model of Factors Correlated to Homeownership: The Case of Utah

    FAMILY & CONSUMER SCIENCES RESEARCH JOURNAL, Issue 1 2001
    Lucy Delgadillo
    This article examines the relationship between homeownership and socioeconomic, demographic, and market factors in Utah. Units of analyses were census-designated places. The goal was to provide a model that can be replicated by housing specialists and consumer scientists to gain a better understanding of how homeownership (dependent variable) differs from place to place and how this variation relates to socioeconomic index, population density, affordability ratio, and the median value of owner occupied housing units (independent variables). The 1990 data set was analyzed using bivariate and multivariate analyses. Homeownership percentages were regressed on the linear combination of the socioeconomic scale, log of population density, and affordability ratios. Log of population density was the factor that explained most of the variance. The interaction equation slightly improved the explanatory power, accounting for more than 50% of the variance. [source]


    Problem Representation and Conflict Dynamics in the Middle East and Northern Ireland

    FOREIGN POLICY ANALYSIS, Issue 3 2005
    Donald A. Sylvan
    In an effort to explain conflictual and cooperative actions in the Middle East and Northern Ireland at a time (1995,1999) when international structural factors were relatively constant, this article focuses on cognitive factors. Specifically, statements of leaders representing multiple actors in the Israeli,Palestinian and Northern Ireland relationship are examined. Texts from these leaders serve as data for the independent variable, problem representation. Hypotheses argue that the existence and centrality of actor problem representations can help explain behavior, in a manner that adds to more widely used scholarly explanations. More specifically, the article explores the relationship among leaders' "problem representations" and conflict between the entities they lead. Problem representation is measured in three dimensions using Foreign Broadcast Information Service (World News Connection) texts: (1) centrality of enemy image, (2) how inclusive/exclusive the leader is in describing the in-group and principal outgroup, and (3) the key definition of the problem (coded in terms of three strategies: justice, governance, or threat). Conflict, the dependent variable, is measured in terms of KEDS-TABARI event data on deeds (not words) in the Israeli,Palestinian and Northern Ireland conflicts. Strikingly, the analysis finds that Israeli actions are strongly related to prior and current Palestinian leaders' problem representations, much more than they are to Israeli leaders' problem representations. Similarly, Palestinian actions are found to have a clear relationship with prior and current Israeli leaders' problem representations, much more than they are with Palestinian leaders' problem representations. These results are particularly strong when the problem representation is one of the overall political leadership on the "other" side. Additionally, in-group and out-group inclusivity are the most significant predictors of actions. For Northern Ireland, the same two themes prevail, although not as strongly: there is a clear statistical relationship between each side's problem representations and the other side's actions, stronger in fact than the relationship between their own side's representations and actions. Also, in-group and out-group inclusivity produce a strong statistical relationship with conflict and cooperation. Finally, results are compared with a "tit-for-tat" hypothesis, and found to embellish that hypothesis. [source]


    Stone artifact scatters in western NSW, Australia: Geomorphic controls on artifact size and distribution

    GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2001
    Patricia Fanning
    Surface scatters of Aboriginal stone artifacts have been exposed in many parts of inland Australia by accelerated erosion that followed the introduction of pastoralism by European settlers in the 19th century. This paper reports on a set of techniques developed to investigate and quantify the effects of these post-discard disturbance processes in Sturt National Park in northwest NSW, Australia. Backwards, stepwise, linear regression showed the influence of geomorphic parameters such as slope gradient, elevation, landform, and contemporary surface processes on artifact distribution, with artifact maximum dimension as the dependent variable. The results indicate that, even at low gradients, artifact size and slope angle are significantly related, but that the variance in maximum dimension explained by gradient is very low. Similar results were found for the other geomorphic variables. We conclude that artifact movement by surface wash across these surfaces is unlikely to significantly affect artifact distribution. While vertically conflated surface scatters do not preserve "living floors" in a short-term, functional sense, their apparent horizontal integrity allows investigation of the long-term use of place by hunter-gatherer people in the past. Insofar as assemblage integrity is important for assessing site significance in the heritage management industry, our methods provide a means for assessing the degree to which a site has been damaged by water flow. © 2001 John Wiley & Sons, Inc. [source]


    Characterization of cataclastic shear-zones of the KTB deep drill hole by regression analysis of drill cuttings data

    GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002
    Helmuth Winter
    Summary During the course of the German continental deep drilling project (KTB) two scientific drill holes were drilled, the KTB Vorbohrung down to 4 km and the KTB Hauptbohrung down to 9.1 km, both intersecting several cataclastic shear-zones. As few drill cores were available in the KTB Hauptbohrung, most of the petrophysical and geochemical data are based on drill cuttings investigations. We present an analysis of drill cuttings data, addressing the question of what relationship between cataclastic shear-zones and petrophysical and geochemical data can be revealed. For that purpose we developed a regression model with the amount of cataclastic rocks in drill cuttings as a dependent variable and the petrophysical and geochemical variables as regressors. We use depth related data from two sections of the KTB Hauptbohrung with cataclastic shear-zones in gneiss (1738,2380 m) and in metabasite (4524,4908 m). The variables are selected by estimating and testing a linear regression model taking into account the autocorrelation of the data due to the depth structure. The variables which characterize the cataclastic shear-zones in gneiss according to our model are the contents of carbon and crystal water and the thermal conductivity, each with positive coefficients. This model explains, in total, 57 per cent of the variance of the observed data. For cataclastic shear-zones in metabasite the content of crystal water and the magnetic susceptibility with positive coefficients and the content of chromium with a negative coefficient are the significant variables. The explained variance in this model is 60 per cent. Being significant in both lithologies, the content of crystal water is an important variable for cataclastic shear-zones. The prediction of shear zones is feasible by our methods, but the results of our study should be confirmed and widened by investigations of other data sets. [source]


    Relation of hypertension and glucose tolerance impairment in elderly people to the development of arteriosclerosis: Investigation using pulse wave velocity,

    GERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 1 2005
    Takeshi Isobe
    Background: The aim of the present study was to determine the correlation between the combination of hypertension and diabetes mellitus and arteriosclerosis using pulse wave velocity (PWV). Methods: The subjects were 186 men over the age of 60 years (mean age: 68.8 ± 5.8 years). PWV, systolic blood pressure (SBP), diastolic blood pressure, body mass index, fasting blood sugar (FBS), total cholesterol, triglyceride and HDL cholesterol were measured in all subjects. The subjects were divided into three groups on the basis of FBS level: a normal group (FBS < 110 mg/dL), an impaired fasting glucose group (110 , FBS < 126 mg/dL) and a diabetes mellitus group (FBS , 126 mg/dL or taking antidiabetics). The subjects were also divided into two groups on the basis of blood pressure level: a hypertension (HT) group (SBP , 140 mmHg and/or diastolic blood pressure , 90 mmHg or taking antihypertensives) and a normotension group (other subjects). Results: PWV showed positive correlations with SBP and FBS (r = 0.499 and r = 0.300, respectively). In all three groups classified by FBS level, PWV was higher in subjects with HT than in subjects with normotension (P < 0.01 in all three groups). In the HT group, PWV had already increased at the stage of impaired fasting glucose and was significantly higher in the diabetes mellitus group than in the normal FBS group (P = 0.002). In multiple regression analysis using PWV as a dependent variable, SBP and FBS were selected as independent variables. Conclusions: Even in the elderly, strict control of blood pressure and blood sugar level may be necessary in order to prevent the development of arteriosclerotic diseases. [source]


    The pervasive influence of sampling and methodological artefacts on a macroecological pattern: the abundance,occupancy relationship

    GLOBAL ECOLOGY, Issue 4 2008
    Peter D. Wilson
    ABSTRACT Aim To investigate the influence of sampling and methodological artefacts on the correlation between abundance and occupancy. Location Global scope. Methods A fixed effects weighted regression model was fitted to standardized effect size for 175 examples of correlations between abundance and occupancy. A regression tree model with standard effect size as the dependent variable was also fitted to the data. Results Standard effect size, and therefore the correlation between abundance and occupancy, was found to be strongly influenced by the type of abundance measure used to characterize the abundance,occupancy relationship. Local mean abundance (also referred to as ecological mean abundance) was primarily responsible for negative correlations. Negative correlations also resulted from a mismatch in the sampling extents of abundance and occupancy measures. Main conclusions The combination of abundance and occupancy measures selected to characterize the abundance,occupancy relationship for a given set of data has a profound impact on the sign of the correlation between the selected measures. Previous attempts to understand the processes giving rise to the pattern represented by the abundance,occupancy relationship have confounded sampling artefacts (e.g. spatial extent of abundance and occupancy information) and methodological artefacts (e.g. combining a truncated abundance measure such as local mean abundance with an untruncated occupancy measure such as proportion of occupied samples). Thus, a revision of the approach currently used to define and evaluate competing explanatory models of the abundance,occupancy relationship appears to be necessary. [source]