956 resultados para Variance-covariance Matrices


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The aim of the paper is to obtain some theoretical and numerical properties of Saaty’s and Koczkodaj’s inconsistencies of pairwise comparison matrices (PRM). In the case of 3 × 3 PRM, a differentiable one-to-one correspondence is given between Saaty’s inconsistency ratio and Koczkodaj’s inconsistency index based on the elements of PRM. In order to make a comparison of Saaty’s and Koczkodaj’s inconsistencies for 4 × 4 pairwise comparison matrices, the average value of the maximal eigenvalues of randomly generated n × n PRM is formulated, the elements aij (i < j) of which were randomly chosen from the ratio scale ... ... with equal probability 1/(2M − 1) and a ji is defined as 1/a ij . By statistical analysis, the empirical distributions of the maximal eigenvalues of the PRM depending on the dimension number are obtained. As the dimension number increases, the shape of distributions gets similar to that of the normal ones. Finally, the inconsistency of asymmetry is dealt with, showing a different type of inconsistency.

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Pairwise comparison matrices are often used in Multi-attribute Decision Making forweighting the attributes or for the evaluation of the alternatives with respect to a criteria. Matrices provided by the decision makers are rarely consistent and it is important to index the degree of inconsistency. In the paper, the minimal number of matrix elements by the modification of which the pairwise comparison matrix can be made consistent is examined. From practical point of view, the modification of 1, 2, or, for larger matrices, 3 elements seems to be relevant. These cases are characterized by using the graph representation of the matrices. Empirical examples illustrate that pairwise comparison matrices that can be made consistent by the modification of a few elements are present in the applications.

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A special class of preferences, given by a directed acyclic graph, is considered. They are represented by incomplete pairwise comparison matrices as only partial information is available: for some pairs no comparison is given in the graph. A weighting method satisfies the property linear order preservation if it always results in a ranking such that an alternative directly preferred to another does not have a lower rank. We study whether two procedures, the Eigenvector Method and the Logarithmic Least Squares Method meet this axiom. Both weighting methods break linear order preservation, moreover, the ranking according to the Eigenvector Method depends on the incomplete pairwise comparison representation chosen.

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This dissertation analyzes whether and how changes in federal tax policy affect local tax policies, specifically, the elimination of the federal deductibility of state and local taxes for individual taxpayers by the Tax Reform Act of 1986 (TRA86) in 59 California cities. Two methods are used in the study: a survey of local revenue officials and a time event time-series/cross sectional sales tax reliance study.^ The reliance study uses a covariance model to pool cross-section and time-series observations. The results of the reliance study indicate a statistically significant overall decline in sales tax reliance after 1986. The results of the survey indicate that local policy makers generally do not believe that federal deductibility is an important factor when considering raising local sales taxes. Further analysis shows that local revenue officials claiming federal deductibility is not an important factor are associated mostly with cities that registered no significant decline in sales tax reliance after 1986. Similarly, local revenue officials claiming federal deductibility is an important factor when considering local tax policy are associated mostly with cities that suffered a significant decline in sales tax reliance after 1986.^ Of that group, further analysis shows that the declines in sales tax reliance are associated mostly with cities located in the southwestern part of the state. When compared to other cities in the state, an analysis of variance reveals that there are a series of statistically significant factors associated with southwestern cities which may contribute to the decline in sales tax reliance following the enactment of the Tax Reform Act of 1986. ^

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It was hypothesized that making a commute elevates blood pressure, causes negative affect, reduces frustration tolerance, and impairs performance on simple and complex cognitive tasks. This hypothesis was tested by varying choice and type of commute in an experiment in which 168 volunteers were randomly assigned to one of six experimental conditions. The behavior of subjects who drove 30 miles or rode on a bus for the same distance were compared with the reactions of students who did not commute. Multivariate analyses of variance indicated that subjects who made the commute showed lower frustration tolerance and deficits on complex cognitive task performance. Commuting also raised pulse and systolic blood pressure. Multivariate analyses of covariance (MANCOVA) were performed in an effort to identify physiological and emotional reactions that may mediate these relations. No mediational relationships were uncovered. ^

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The purpose of this dissertation was to examine the form of the consumer satisfaction/dissatisfaction (CS/D) response to disconfirmation. In addition, the cognitive and affective processes underlying the response were also explored. ^ Respondents were provided with information from a prior market research study about a new brand of printer that was being tested. This market research information helped set prior expectations regarding the print quality. Subjects were randomly assigned to an experimental condition that manipulated prior expectations to be either positive or negative. Respondents were then provided with printouts that had performance quality that was either worse (negative disconfirmation) or better (positive disconfirmation) than the prior expectations. In other words, for each level of expectation, respondents were assigned to either positive or negative disconfirmation condition. Subjects were also randomly assigned to a condition of either a high or low level of outcome involvement. ^ Analyses of variance indicated that positive disconfirmation led to a more intense CS/D response than negative disconfirmation, even though there was no significant difference in the intensity for positive and negative disconfirmation. Intensity of CS/D was measured by the distance of the CS/D rating from the midpoint of the scale. The study also found that although outcome involvement did not influence the polarity of the CS/D response, the more direct measures of processing involvement such as the subjects' concentration, attention and care in evaluating the printout did have a significant positive effect on CS/D intensity. ^ Analyses of covariance also indicated that the relationship between the intensity of the CS/D response and the intensity of the disconfirmation was mediated by the intensity of affective responses. Positive disconfirmation led to more intense affective responses than negative disconfirmation. ^

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The purpose of this quasi-experimental study was to explore the perceived effects of the Ropes Course on the performance of intact work teams. The dependent variable, team performance, was measured by the Team Performance Assessment, a 20 question inventory. The Ropes Course, the independent variable, was an outdoor experiential training program presently marketed as a highly effective team building training program. Issues the team addressed in the highly emotional and physical environment were purported to transfer back to the work environment and act as a catalyst for change The Ropes Course in this study consisted of a day long series of outdoor mental, emotional and physical exercises addressing the issues of goal-setting, role expectations, accountability, trust, respect, communication, problem-solving and decision-making. The 68 subjects, 37 in the treatment group and 31 in the control were employees of a large international financial institution. They were not chosen by random selection. The work teams' managers recognized a need to improve team morale, performance and functioning due to corporate reengineering and downsizing resulting in team members' job losses. Control teams were partially matched to the treatment teams on the basis of professional composition and similar job descriptions. The pretest of the Team Performance Assessment was given the morning of the Ropes Course treatment and the posttest was given three to five weeks later. The control teams received the pretests and posttests at about the same time intervals at their work location but received no Ropes Course treatment. The treatment teams' scores and the control teams' scores were statistically compared using the Multivariate Analysis of Variance (MANOVA) and the Multivariate Analysis of Covariance (MANCOVA) at the .05 level of significance. The statistical analysis revealed a significant difference between the control and experimental teams after the team building Ropes Course training as measured by the Team Performance Assessment (Gilbert, 1996). ^

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The effects of lead exposure may endure through one's lifetime and can negatively effect educational performance. While the link between the cause and effects of lead poisoning has been identified, the application of lead health education as the mechanism of disease prevention has not. The purpose of this study was to examine whether caregiver participation in a family-based educational intervention can result in decreased lead exposure in low socioeconomic children. ^ Participants (n = 50) were caregivers of children 12 to 36 months of age. They were randomly selected from an urban clinic and randomly assigned to either a treatment or control group. The experimental design of this study involved two clinic visits. Parents in the treatment group were given the educational intervention during the first clinic visit while those in the control group were given the intervention during the second clinic visit. The intervention was reinforced with a lead education brochure coupled with a video on childhood lead poisoning. One instrument was used to test parental knowledge of lead poisoning both pre- and post-intervention. Blood lead levels in pediatric participants were tested using two blood lead screens approximately three to four months apart determined by well-child check-up schedules. ^ Findings from the analysis of variance showed the interaction between the change in blood lead level between the children's first and second clinic visits and the treatment level. This demonstrated a significant interaction between the differences of first and second clinic visits blood lead levels and the presence or absence of the educational intervention. ^ The findings from an analysis of covariance support that caregivers in the treatment group have significantly higher scores on the second clinic visit scores on the CLKT than the caregivers in the control group. These data suggest that the educational treatment is effective in increasing the knowledge of caregivers about the dangers of lead poisoning and the strategies for lead poisoning prevention. ^ Conclusions indicate that the education of adult caregivers can affect blood lead levels of children, the educational treatment increased the knowledge of caregivers, caregivers were able to carry out procedures taught, and caregivers retained knowledge over time. ^

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The primary research question was: What is the nature and degree of alignment between the tenets of learning organizations and the policies and practices of a community college concerning adjunct instructors? I investigated the employment experiences of 8 adjunct instructors at a large community college in the Southeastern U.S. to (a) describe and explain the perspectives of the adjuncts, (b) describe and explain my own adjunct employment experience at the same college, (c) determine how the adjunct policies and practices collectively encountered were congruent with or at variance with the tenets of learning organizations, and (d) to use this framework to support recommendations that may help the college achieve more favorable alignment with these tenets. ^ Data on perceived adjunct policies and practices were reduced into 11 categories and, using matrices, were compared with 5 major categories of learning organization tenets. The 5 categories of tenets were: (a) inputs, (b) information flow/communication, (c) employee inclusion/value, (d) teamwork, and (e) facilitation of change. The 11 categories of the college's policies and practices were (a) becoming an adjunct, (b) full-time employment aspirations, (c) salary, (d) benefits, (e) job security and predictability, (f) job satisfaction, (g) respect, (h) support services, (i) professional development, (j) institutional inclusion, and (k) future role of adjuncts. The reflective journal component relied on a 5-year (1995–2000) personal and professional journal maintained by me during employment with the same college as the participants. ^ Findings indicate that the college's adjunct policies and practices were most incongruent with 25 of the 70 learning organization tenets. These incongruencies spanned the 5 categories, although most occurred in the Employee/Inclusion/Value category. Adjunct instructors wanted inclusion, respect, value, trust, and empowerment in decision making processes that affect adjunct policies and practices of the college, but did not perceive this to be a part of the present situation. ^

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We develop a new autoregressive conditional process to capture both the changes and the persistency of the intraday seasonal (U-shape) pattern of volatility in essay 1. Unlike other procedures, this approach allows for the intraday volatility pattern to change over time without the filtering process injecting a spurious pattern of noise into the filtered series. We show that prior deterministic filtering procedures are special cases of the autoregressive conditional filtering process presented here. Lagrange multiplier tests prove that the stochastic seasonal variance component is statistically significant. Specification tests using the correlogram and cross-spectral analyses prove the reliability of the autoregressive conditional filtering process. In essay 2 we develop a new methodology to decompose return variance in order to examine the informativeness embedded in the return series. The variance is decomposed into the information arrival component and the noise factor component. This decomposition methodology differs from previous studies in that both the informational variance and the noise variance are time-varying. Furthermore, the covariance of the informational component and the noisy component is no longer restricted to be zero. The resultant measure of price informativeness is defined as the informational variance divided by the total variance of the returns. The noisy rational expectations model predicts that uninformed traders react to price changes more than informed traders, since uninformed traders cannot distinguish between price changes caused by information arrivals and price changes caused by noise. This hypothesis is tested in essay 3 using intraday data with the intraday seasonal volatility component removed, as based on the procedure in the first essay. The resultant seasonally adjusted variance series is decomposed into components caused by unexpected information arrivals and by noise in order to examine informativeness.

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This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. This image is made available for non-commercial or educational use only.

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This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. This image is made available for non-commercial or educational use only.

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There are situations in which it is very important to quickly and positively identify an individual. Examples include suspects detained in the neighborhood of a bombing or terrorist incident, individuals detained attempting to enter or leave the country, and victims of mass disasters. Systems utilized for these purposes must be fast, portable, and easy to maintain. The goal of this project was to develop an ultra fast, direct PCR method for forensic genotyping of oral swabs. The procedure developed eliminates the need for cellular digestion and extraction of the sample by performing those steps in the PCR tube itself. Then, special high-speed polymerases are added which are capable of amplifying a newly developed 7 loci multiplex in under 16 minutes. Following the amplification, a postage stamp sized microfluidic device equipped with specially designed entangled polymer separation matrix, yields a complete genotype in 80 seconds. The entire process is rapid and reliable, reducing the time from sample to genotype from 1-2 days to under 20 minutes. Operation requires minimal equipment and can be easily performed with a small high-speed thermal-cycler, reagents, and a microfluidic device with a laptop. The system was optimized and validated using a number of test parameters and a small test population. The overall precision was better than 0.17 bp and provided a power of discrimination greater than 1 in 106. The small footprint, and ease of use will permit this system to be an effective tool to quickly screen and identify individuals detained at ports of entry, police stations and remote locations. The system is robust, portable and demonstrates to the forensic community a simple solution to the problem of rapid determination of genetic identity.

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The purpose of this research was to investigate the relationship of computer anxiety to selected demographic variables: learning styles, age, gender, ethnicity, teaching/professional areas, educational level, and school types among vocational-technical educators.^ The subjects (n = 202) were randomly selected vocational-technical educators from Dade County Public School System, Florida, stratified across teaching/professional areas. All subjects received the same survey package in the spring of 1996. Subjects self-reported their learning style and level of computer anxiety by completing Kolb's Learning Style Inventory (LSI) and Oetting's Computer Anxiety Scale (COMPAS, Short Form). Subjects' general demographic information and their experience with computers were collected through a self-reported Participant Inventory Form.^ The distribution of scores suggested that some educators (25%) experienced some overall computer anxiety. There were significant correlations between computer related experience as indicated by self-ranked computer competence and computer based training and computer anxiety. One-way analyses of variance (ANOVA) indicated no significant differences between computer anxiety and/or computer related experiences, and learning style, age, and ethnicity. There were significant differences between educational level, teaching area, school type, and computer anxiety and/or computer related experiences. T-tests indicated significant differences between gender and computer related experiences. However, there was no difference between gender and computer anxiety.^ Analyses of covariance (ANCOVA) were performed for each independent variable on computer anxiety, with computer related experiences (self-ranked computer competence and computer based training) as the respective covariates. There were significant main effects for the educational level and school type on computer anxiety. All other variables were insignificant on computer anxiety. ANCOVA also revealed an effect for learning style varied notably on computer anxiety. All analyses were conducted at the.05 level of significance. ^

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Arthritis is the most common chronic condition affecting older people and is a major cause of limited activity. Arthritis education programs in English have demonstrated a positive impact on health but these programs have not reached the Hispanic communities where arthritis is the leading cause of disability. Minorities, such as Hispanics, have traditionally been reluctant to pursue self-help programs, and have been identified as an under-served population in terms of medical care. This study examined the effectiveness of one community health adult education program targeting Hispanic older adults with arthritis, the Spanish Arthritis Self Management Education Program (SASMEP), by evaluating changes in the participants' general health, pain, disability, self-efficacy, health perceptions, frequency of physician visits, and exercise. A pre and post control group experimental design and analyses of covariance were used to determine the pre and post differences in health status and health behaviors for a group participating in the SASMEP and a group who did not using gender and age as covariates. A repeated measures design was also used, and repeated measures analyses of variance and post hoc tests were done on health status and health behavior data collected pre, post and one-year post education to determine long-term differences. ^ Results indicated the participants' health status significantly improved in general health, significantly decreased in pain, and significantly decreased in arthritic disability immediately following the education. Self-efficacy and health perceptions increased for both groups but not significantly. The participants' health behaviors showed significantly fewer physician visits and significantly increased time spent performing stretching and strengthening exercise and time spent performing aerobic exercise. No group differences were found in the frequency of arthritis physician visits. ^ The improvements seen immediately after the SASMEP participation were not reflected in the post one-year scores. No significant differences were found for the participants' health status or health behaviors one year following the education. Health status and health behaviors did not return below baseline scores after one year suggesting the participants' health, although not improved, did not deteriorate. Therefore, the SASMEP education provided short-term health benefits for older Hispanic adults with arthritis, but not long-term health benefits. ^