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Path Models (path + models)
Selected AbstractsCognitive function, P3a/P3b brain potentials, and cortical thickness in agingHUMAN BRAIN MAPPING, Issue 11 2007Anders M. Fjell Abstract The purpose of the study was to assess the relationship between the P3a/P3b brain potentials, cortical thickness, and cognitive function in aging. Thirty-five younger and 37 older healthy participants completed a visual three-stimuli oddball ERP (event-related potential)-paradigm, a battery of neuropsychological tests, and MRI scans. Groups with short vs. long latency, and low vs. high amplitude, were compared on a point by point basis across the entire cortical mantle. In the young, thickness was only weakly related to P3. In the elderly, P3a amplitude effects were found in parietal areas, the temporoparietal junction, and parts of the posterior cingulate cortex. P3b latency was especially related to cortical thickness in large frontal regions. Path models with the whole sample pooled together were constructed, demonstrating that cortical thickness in the temporoparietal cortex predicted P3a amplitude, which in turn predicted executive function, and that thickness in orbitofrontal cortex predicted P3b latency, which in turn predicted fluid function. When age was included in the model, the relationship between P3 and cognitive function vanished, while the relationship between regional cortical thickness and P3 remained. It is concluded that thickness in specific cortical areas correlates with scalp recorded P3a/P3b in elderly, and that these relationships differentially mediate higher cognitive function. Hum Brain Mapp 2007. © 2007 Wiley-Liss, Inc. [source] Investigating the relationship between past contraceptive behaviour, self-efficacy, and anticipated shame and guilt in sexual contexts among Norwegian adolescentsJOURNAL OF COMMUNITY & APPLIED SOCIAL PSYCHOLOGY, Issue 1 2007Bente Træen Abstract What are the relationships between self-efficacy when communicating to the partner about use of contraception, stopping undesired intercourse, and perceived self-conscious emotions in sexual contexts? How does past contraceptive behaviour influence perceived self-efficacy? These research questions were studied among 399 10th grade students with coital experience in the county Nordland in Norway. Two dimensions of perceived emotional responses were identified in a hypothetical situation related to communicating to the partner about use of contraception, namely Shame and Emotional intimacy. Two dimensions were also identified with regard to anticipated emotional responses in a hypothetical situation related to stopping undesired intercourse: Guilt and responsibility and Emotional intimacy. Most of the boys and girls reported that they would react with positive emotions in both hypothetical situations. Path models were constructed with the affective dimensions and self-esteem as mediating variables between past contraceptive behaviour and contextual self-efficacy. Past behaviour influenced communication self-efficacy indirectly via Shame, and Shame had a direct effect upon self-efficacy. Guilt and responsibility had a direct effect upon stop-self-efficacy. Copyright © 2006 John Wiley & Sons Ltd. [source] Numerical modeling of hydrothermal zinc silicate and sulfide mineralization in the Vazante deposit, BrazilGEOFLUIDS (ELECTRONIC), Issue 2 2009M. S. APPOLD Abstract The Vazante zinc deposit in central Brazil is currently the world's largest known example of a hypogene nonsulfide (i.e. willemite-dominant) zinc deposit. The mineralization is hypothesized to have formed as a result of mixing between a hot, acidic, reducing, metal-rich brine and a cool, more basic and dilute, metal-poor meteoric fluid. The present study sought to investigate this scenario by quantifying the individual effects of temperature, pH, salinity, and oxidation state on willemite and sphalerite solubility, and modeling their combined effects during mixing through reaction path and reactive transport modeling. Solubility calculations showed that in an initially hot, moderately acidic, reducing, metal-rich ore fluid saturated with respect to silica, willemite solubility is relatively insensitive to changes in temperature and log , but highly sensitive to changes in pH and salinity. In contrast, sphalerite solubility was highly sensitive to changes in temperature and log , as well as salinity, and was less sensitive than willemite to changes in pH. Reaction path models sought to extend these observations by modeling the geochemistry of mixing. The results show that mixing is able to produce most of the major zinc ore and gangue minerals observed in the field, though not necessarily at the same paragenetic stages, and that both compositional and temperature changes from mixing are needed. Reactive transport models were formulated to investigate spatial patterns of mineralization. The results showed that sphalerite deposition was strongly controlled by temperature and concentrated in the regions of greatest temperature change. Willemite deposition was concentrated along the interface between the metal-rich ore fluid and the surrounding meteoric fluid. The more rapid transport of solute than heat, in conjunction with the higher concentration of silica than sulfide in both fluids meant that willemite mineralization developed over a broader region and in greater concentrations compared with sphalerite. [source] Multi-block and path modelling proceduresJOURNAL OF CHEMOMETRICS, Issue 11-12 2008Agnar Höskuldsson Abstract The author has developed a unified theory of path and multi-block modelling of data. The data blocks are arranged in a directional path. Each data block can lead to one or more data blocks. It is assumed that there is given a collection of input data blocks. Each of them is supposed to describe one or more intermediate data blocks. The output data blocks are those that are at the ends of the paths and have no succeeding data blocks. The optimisation procedure finds weights for the input data blocks so that the size of the total loadings for the output data blocks are maximised. When the optimal weight vectors have been determined, the score and loading vectors for the data blocks in the path are determined. Appropriate adjustment of the data blocks is carried out at each step. Regression coefficients are computed for each data block that show how the data block is estimated by data blocks that lead to it. Methods of standard regression analysis are extended to this type of modelling. Three types of ,strengths' of relationship are computed for each set of two connected data blocks. First is the strength in the path, second the strength where only the data blocks leading to the last one are used and third if only the two are considered. Cross-validation and other standard methods of linear regression are carried out in a similar manner. In industry, processes are organised in different ways. It can be useful to model the processes in the way they are carried out. By proper alignment of sub-processes, overall model can be specified. There can be several useful path models during the process, where the data blocks in a path are the ones that are actual or important at given stages of the process. Data collection equipments are getting more and more advanced and cheap. Data analysis need to ,catch up' with the challenges that these new technology provides with. Copyright © 2008 John Wiley & Sons, Ltd. [source] Behind the Third-Person Effect: Differentiating Perceptual Processes for Self and OtherJOURNAL OF COMMUNICATION, Issue 4 2001Douglas M. McLeod This study investigated factors related to two types of judgments that make up the third-person perception: media effects on others and effects on self. Specifically, separate regression path models revealed that estimates of effects on others are based on a relatively naive schema for media effects that is similar to the "magic bullet" model of media effects (i.e., more exposure leads to greater effects). On the other hand, assessing effects on self involves a more complex, conditional effects model. The different pattern of results for the self and other models reflect the "fundamental attribution error" from attribution theory. The path models also extend results from the perceptual component to the behavioral component of the third-person effect by linking the explanatory variables to support for censorship. Both models showed that paternalistic attitudes were the strongest predictor of support for censorship. [source] Spatio-temporal variation in fruit production and seed predation in a perennial herb influenced by habitat quality and population sizeJOURNAL OF ECOLOGY, Issue 2 2008Jon Ågren Summary 1In patchily distributed plant species, seed production is likely to be influenced both by local abiotic factors affecting plant size and conditions for fruit maturation, and by population characteristics affecting the intensity of interactions with mutualists and antagonists. However, the relative importance of these effects is poorly known. 2We used multiple regression and path models to examine the importance of abiotic factors (sun exposure, soil depth) and population characteristics (size, density and connectivity) for variation in flower and fruit production and intensity of seed predation among 39 populations of the long-lived herb Vincetoxicum hirundinaria in three consecutive years. In addition, we manipulated water availability in a field experiment and recorded short-term and long-term effects on fruit output, and conducted a supplemental hand-pollination experiment. 3Flower production varied little, while fruit initiation, fruit abortion and fruit predation varied considerably among years. Sun exposure and soil depth affected fruit production per plant indirectly and positively through their effects on flower number. Population density affected fruit production negatively through its effect on flower number. Both fruit initiation and the proportion of fruits attacked by the tephritid fly Euphranta connexa were related positively to population size. 4The number of full-size fruits per plant was related positively to sun exposure and population size in two years each, and related negatively to population density in one year. However, because of seed predation, the number of intact mature fruits was related significantly to population characteristics in only one of three years. 5The field experiments showed that both shortage of water and insufficient pollination may limit fruit set in V. hirundinaria. 6Synthesis. These results demonstrate that the relative importance of local abiotic conditions and population characteristics may vary considerably along the chain of events from flower formation to intact fruit, and also among years. They further show that, at least in species with a naturally patchy distribution, connectivity may be relatively unimportant for variation in reproductive output compared to effects of habitat quality, population size and density. [source] Longitudinal Associations Between Personality Profile Stability and Adjustment in College Students: Distinguishing Among Overall Stability, Distinctive Stability, and Within-Time NormativenessJOURNAL OF PERSONALITY, Issue 4 2010Theo A. Klimstra ABSTRACT In the present study, longitudinal associations of 3 aspects of personality profile stability (i.e., overall stability, distinctive stability, and within-time normativeness) with 3 adjustment measures (i.e., depressive symptoms, self-esteem, and delinquency) were examined, using 4 waves of longitudinal data on a Belgian college sample (N=565). Longitudinal path models revealed strong longitudinal associations between adjustment and overall stability. Subsequent analyses showed that it is not the degree to which one's personality profile consistently diverges from the average personality profile within a population (i.e., distinctive stability) that is related to adjustment but the degree to which a personality profile of an individual matches the average personality profile within the sample at a certain point in time (i.e., within-time normativeness). The current study thereby underscores the importance of distinguishing normativeness and distinctiveness when examining personality profile stability. [source] The Role of Youth Problem Behaviors in the Path From Child Abuse and Neglect to Prostitution: A Prospective ExaminationJOURNAL OF RESEARCH ON ADOLESCENCE, Issue 1 2010Helen W. Wilson Behaviors beginning in childhood or adolescence may mediate the relationship between childhood maltreatment and involvement in prostitution. This paper examines 5 potential mediators: early sexual initiation, running away, juvenile crime, school problems, and early drug use. Using a prospective cohort design, abused and neglected children (ages 0,11) with cases processed during 1967,1971 were matched with nonabused, nonneglected children and followed into young adulthood. Data are from in-person interviews at approximately age 29 and arrest records through 1994. Structural equation modeling tested path models. Results indicated that victims of child abuse and neglect were at increased risk for all problem behaviors except drug use. In the full model, only early sexual initiation remained significant as a mediator in the pathway from child abuse and neglect to prostitution. Findings were generally consistent for physical and sexual abuse and neglect. These findings suggest that interventions to reduce problem behaviors among maltreated children may also reduce their risk for prostitution later in life. [source] Well-being of mothers of children with mental retardation: An evaluation of the Double ABCX model in a cross-cultural contextASIAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 3 2003Jin Y. Shin The present study was designed to compare the psychological well-being of mothers of children with mental retardation in the USA and Korea. The Double ABCX model of stress proposed by McCubbin and Patterson (1983) was evaluated for the two national groups. Thirty-eight American and 40 Korean mothers participated in the home-visit interview. The path models in the present study partially supported the ABCX model, but different path models for the two national groups provided important explanations for the well-being of mothers from the two nations. The cause of stress for the American mothers was specific to the individual variables. For Korean mothers, cultural values that carry social influence were more strongly associated with their attitudes towards the child and their experience of stress. [source] Causal Links Between Financial Activity and Economic Growth: Empirical Evidence from a Cross,Country Analysis, 1970,1990BULLETIN OF ECONOMIC RESEARCH, Issue 2 2002Michael Graff To clarify the causal links between financial activity and economic growth, a series of path models is estimated. It is shown that during the 1970s and 1980s finance was predominantly a supply,leading determinant of economic growth. The data suggest, however, that there has been a structural change and that from about 1975,80, finance was far less beneficial , and possibly even detrimental , to growth. [source] Entering the Political Elite in Canada: The Case of Minority Women as Parliamentary Candidates and MPs,CANADIAN REVIEW OF SOCIOLOGY/REVUE CANADIENNE DE SOCIOLOGIE, Issue 2 2000Jerome H. Black Cette recherche analyse les femmes des minorités ethniques comme nouveau groupe social visant à accéder à l'élite politique. Elle est axée sur les conséquences liées à leur appartenance à une «double minorité». L'analyse examine deux modèles de cheminement de carrière qui offrent des caractérisations alternatives quant aux obstacles de recrutement auxquels se heurtent les nouveaux groupes sociaux et qui créent des attentes différentes quant aux ressources détenues par les femmes des minorités, comparativement à celles des groupes plus établis. Les résultats principaux, fondés sur un sondage canadien de 1993 sur les candidats parlementaires et completés par de l'information sur les députés, appuient davantage le modèle de «compensation» et, en général, semblent indiquer que l'inégalité continue de caractériser le processus d'accès à l'élite politique. This study examines minority women as a new social group seeking access to the political elite, emphasizing the consequences of their "double minority" status. The analysis considers two career path models that make alternative characterizations about the recruitment barriers faced by new social groups and that yield different expectations about the resources held by minority women compared with more established groups. The main results, based on a 1993 Canadian survey of parliamentary candidates, supplemented by information on MPs, indicate more support for the "compensation" model and, generally, suggest that inequity continues to characterize the process of political elite access. [source] Peer Rejection, Aggressive or Withdrawn Behavior, and Psychological Maladjustment from Ages 5 to 12: An Examination of Four Predictive ModelsCHILD DEVELOPMENT, Issue 4 2006Gary W. Ladd Findings yielded a comprehensive portrait of the predictive relations among children's aggressive or withdrawn behaviors, peer rejection, and psychological maladjustment across the 5,12 age period. Examination of peer rejection in different variable contexts and across repeated intervals throughout childhood revealed differences in the timing, strength, and consistency of this risk factor as a distinct (additive) predictor of externalizing versus internalizing problems. In conjunction with aggressive behavior, peer rejection proved to be a stronger additive predictor of externalizing problems during early rather than later childhood. Relative to withdrawn behavior, rejection's efficacy as a distinct predictor of internalizing problems was significant early in childhood and increased progressively thereafter. These additive path models fit the data better than did disorder-driven or transactional models. [source] Key worker services for disabled children: what characteristics of services lead to better outcomes for children and families?CHILD: CARE, HEALTH AND DEVELOPMENT, Issue 2 2006P. Sloper Abstract Background, Research has shown that families of disabled children who have a key worker benefit from this service and recent policy initiatives emphasize the importance of such services. However, research is lacking on which characteristics of key worker schemes for disabled children are related to better outcomes for families. Methods, A postal questionnaire was completed by 189 parents with disabled children who were receiving a service in seven key worker schemes in England and Wales. Path analysis was used to investigate associations between characteristics of the services and outcomes for families (satisfaction with the service, impact of key worker on quality of life, parent unmet need, child unmet need). Results, The four path models showed that key workers carrying out more aspects of the key worker role, appropriate amounts of contact with key workers, regular training, supervision and peer support for key workers, and having a dedicated service manager and a clear job description for key workers were associated with better outcomes for families. Characteristics of services had only a small impact on child unmet need, suggesting that other aspects of services were affecting child unmet need. Conclusions, Implications for policy and practice are discussed, including the need for regular training, supervision and peer support for key workers and negotiated time and resources for them to carry out the role. These influence the extent to which key workers carry out all aspects of the key worker's role and their amount of contact with families, which in turn impact on outcomes. [source] | ||||||||||||||||