29 resultados para multi-way analysis

em Digital Commons at Florida International University


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In finance literature many economic theories and models have been proposed to explain and estimate the relationship between risk and return. Assuming risk averseness and rational behavior on part of the investor, the models are developed which are supposed to help in forming efficient portfolios that either maximize (minimize) the expected rate of return (risk) for a given level of risk (rates of return). One of the most used models to form these efficient portfolios is the Sharpe's Capital Asset Pricing Model (CAPM). In the development of this model it is assumed that the investors have homogeneous expectations about the future probability distribution of the rates of return. That is, every investor assumes the same values of the parameters of the probability distribution. Likewise financial volatility homogeneity is commonly assumed, where volatility is taken as investment risk which is usually measured by the variance of the rates of return. Typically the square root of the variance is used to define financial volatility, furthermore it is also often assumed that the data generating process is made of independent and identically distributed random variables. This again implies that financial volatility is measured from homogeneous time series with stationary parameters. In this dissertation, we investigate the assumptions of homogeneity of market agents and provide evidence for the case of heterogeneity in market participants' information, objectives, and expectations about the parameters of the probability distribution of prices as given by the differences in the empirical distributions corresponding to different time scales, which in this study are associated with different classes of investors, as well as demonstrate that statistical properties of the underlying data generating processes including the volatility in the rates of return are quite heterogeneous. In other words, we provide empirical evidence against the traditional views about homogeneity using non-parametric wavelet analysis on trading data, The results show heterogeneity of financial volatility at different time scales, and time-scale is one of the most important aspects in which trading behavior differs. In fact we conclude that heterogeneity as posited by the Heterogeneous Markets Hypothesis is the norm and not the exception.

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This study explored the topic of motivation for intermediate students combining both an objective criterion measure (i.e., standardized test scores) and the self-report of students on self-concept and value of reading. The purpose of this study was to examine how third grade reading achievement correlated with the motivation of fourth grade boys and girls, and, in turn, how motivation related to fourth grade reading achievement. The participants were fourth grade students (n=207) attending two public, elementary schools in Miami-Dade County who were of primarily Hispanic origin or descent. Data were collected using the Reading Survey portion of the Motivation to Read Profile (1996) which measures self-concept and value of reading in order to measure motivation and the Third and Fourth Grade Reading Florida Comprehensive Assessment Tests 2.0 (FCAT 2.0) to assess achievement. First, a one way Analysis of Variance (ANOVA) was conducted to determine whether motivation differed significantly between fourth grade boys and girls. Second, a path analysis was used to determine whether motivation mediated or moderated the association between FCAT 2.0 third and fourth grade scores. Results of the ANOVA indicated that motivation, as measured by the Motivation to Read Profile did not differ significantly by sex. Results from the path analysis indicated that the model was significant and that third grade FCAT 2.0 scores accounted for a significant amount of the variance in fourth grade FCAT 2.0 scores once motivation was entered. Results of the study demonstrated that motivation partially mediates, but does not moderate the relationship between FCAT 2.0 third and fourth grade scores. In conclusion, it can be determined that past student achievement for fourth grade students plays a role in current student achievement when motivation is also considered. It is therefore important in order to improve the quality of fourth grade student's current performance to take into account a student's motivation and past achievement. An effort must be made to address students' motivational needs whether through school wide programs or at the classroom level in addition or in conjunction with cognition. Future research on the effect of self-concept in reading achievement is recommended.

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The elemental analysis of soil is useful in forensic and environmental sciences. Methods were developed and optimized for two laser-based multi-element analysis techniques: laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser-induced breakdown spectroscopy (LIBS). This work represents the first use of a 266 nm laser for forensic soil analysis by LIBS. Sample preparation methods were developed and optimized for a variety of sample types, including pellets for large bulk soil specimens (470 mg) and sediment-laden filters (47 mg), and tape-mounting for small transfer evidence specimens (10 mg). Analytical performance for sediment filter pellets and tape-mounted soils was similar to that achieved with bulk pellets. An inter-laboratory comparison exercise was designed to evaluate the performance of the LA-ICP-MS and LIBS methods, as well as for micro X-ray fluorescence (μXRF), across multiple laboratories. Limits of detection (LODs) were 0.01-23 ppm for LA-ICP-MS, 0.25-574 ppm for LIBS, 16-4400 ppm for μXRF, and well below the levels normally seen in soils. Good intra-laboratory precision (≤ 6 % relative standard deviation (RSD) for LA-ICP-MS; ≤ 8 % for μXRF; ≤ 17 % for LIBS) and inter-laboratory precision (≤ 19 % for LA-ICP-MS; ≤ 25 % for μXRF) were achieved for most elements, which is encouraging for a first inter-laboratory exercise. While LIBS generally has higher LODs and RSDs than LA-ICP-MS, both were capable of generating good quality multi-element data sufficient for discrimination purposes. Multivariate methods using principal components analysis (PCA) and linear discriminant analysis (LDA) were developed for discriminations of soils from different sources. Specimens from different sites that were indistinguishable by color alone were discriminated by elemental analysis. Correct classification rates of 94.5 % or better were achieved in a simulated forensic discrimination of three similar sites for both LIBS and LA-ICP-MS. Results for tape-mounted specimens were nearly identical to those achieved with pellets. Methods were tested on soils from USA, Canada and Tanzania. Within-site heterogeneity was site-specific. Elemental differences were greatest for specimens separated by large distances, even within the same lithology. Elemental profiles can be used to discriminate soils from different locations and narrow down locations even when mineralogy is similar.

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The elemental analysis of soil is useful in forensic and environmental sciences. Methods were developed and optimized for two laser-based multi-element analysis techniques: laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser-induced breakdown spectroscopy (LIBS). This work represents the first use of a 266 nm laser for forensic soil analysis by LIBS. Sample preparation methods were developed and optimized for a variety of sample types, including pellets for large bulk soil specimens (470 mg) and sediment-laden filters (47 mg), and tape-mounting for small transfer evidence specimens (10 mg). Analytical performance for sediment filter pellets and tape-mounted soils was similar to that achieved with bulk pellets. An inter-laboratory comparison exercise was designed to evaluate the performance of the LA-ICP-MS and LIBS methods, as well as for micro X-ray fluorescence (μXRF), across multiple laboratories. Limits of detection (LODs) were 0.01-23 ppm for LA-ICP-MS, 0.25-574 ppm for LIBS, 16-4400 ppm for µXRF, and well below the levels normally seen in soils. Good intra-laboratory precision (≤ 6 % relative standard deviation (RSD) for LA-ICP-MS; ≤ 8 % for µXRF; ≤ 17 % for LIBS) and inter-laboratory precision (≤ 19 % for LA-ICP-MS; ≤ 25 % for µXRF) were achieved for most elements, which is encouraging for a first inter-laboratory exercise. While LIBS generally has higher LODs and RSDs than LA-ICP-MS, both were capable of generating good quality multi-element data sufficient for discrimination purposes. Multivariate methods using principal components analysis (PCA) and linear discriminant analysis (LDA) were developed for discriminations of soils from different sources. Specimens from different sites that were indistinguishable by color alone were discriminated by elemental analysis. Correct classification rates of 94.5 % or better were achieved in a simulated forensic discrimination of three similar sites for both LIBS and LA-ICP-MS. Results for tape-mounted specimens were nearly identical to those achieved with pellets. Methods were tested on soils from USA, Canada and Tanzania. Within-site heterogeneity was site-specific. Elemental differences were greatest for specimens separated by large distances, even within the same lithology. Elemental profiles can be used to discriminate soils from different locations and narrow down locations even when mineralogy is similar.

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The purpose of this study was to assess the knowledge of public school administrators with respect to special education (ESE) law. The study used a sample of 220 public school administrators. A survey instrument was developed consisting of 19 demographic questions and 20 situational scenarios. The scenarios were based on ESE issues of discipline, due process (including IEP procedures), identification, evaluation, placement, and related services. The participants had to decide whether a violation of the ESE child's rights had occurred by marking: (a) Yes, (b) No, or (c) Undecided. An analysis of the scores and demographic information was done using a two-way analysis of variance, chi-square, and crosstabs after a 77% survey response rate.^ Research questions addressed the administrators' overall level of knowledge. Comparisons were made between principals and assistant principals and differences between the levels of schooling. Exploratory questions were concerned with ESE issues deemed problematic by administrators, effects of demographic variables on survey scores, and the listing of resources utilized by administrators to access ESE information.^ The study revealed: (a) a significant difference was found when comparing the number of ESE courses taken and the score on the survey, (b) the top five resources of ESE information were the region office, school ESE department chairs, ESE teachers, county workshops, and county inservices, (c) problematic areas included discipline, evaluation procedures, placement issues, and IEP due process concerns, (d) administrators as a group did not exhibit a satisfactory knowledge of ESE law with a mean score of 12 correct and 74% of responding administrators scoring in the unsatisfactory level (below 70%), (e) across school levels, elementary administrators scored significantly higher than high school administrators, and (f) a significant implication that assistant principals consistently scored higher than principals on each scenario with a significant difference at the high school level.^ The study reveals a vital need for administrators to receive additional preparation in order to possess a basic understanding of ESE school law and how it impacts their respective schools and school districts so that they might meet professional obligations and protect the rights of all individuals involved. Recommendations for this additional administrative preparation and further research topics were discussed. ^

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AIDS education is mandated in schools throughout the United States to educate students about the disease. Teachers are expected to assume the major role of disseminating this information; therefore it is reasonable to question how knowledgeable teachers are about HIV/AIDS and where their information is coming from. This study explored the knowledge and attitudes of general and special education teachers toward students with HIV/AIDS and investigated whether a relationship between knowledge and attitudes existed. Information was collected using the AIDS Knowledge and Attitude Survey (AKAS). The sample was limited to certified teachers resulting in 318 participants.^ Research questions were analyzed using descriptive statistics, frequencies, t-tests, one-way analysis of variance (ANOVA), Scheffe post hoc analysis, and Pearson Product-Moment Correlation. Results indicated that general and special education teachers did not have complete knowledge about HIV/AIDS. Participants were knowledgeable regarding modes of transmission which may be the area of greatest concern for teachers, however, deficiencies were present within teachers' knowledge of general statements and facts and pathology. Among the ten demographic variables analyzed, six (gender, race/ethnicity, level of education, certification, instructional level taught, and classroom AIDS instruction) contained statistical significance.^ Analysis of attitudes indicated that general and special education teachers' overall attitudes toward students with HIV/AIDS were generally positive within clusters of Instruction and Fear, but not within Sensitivity and Communication. Among the ten demographic variables used for analysis only three (age, graduate enrollment status, and classroom AIDS instruction) produced statistical significance. Results found statistically significant relationships between Total Knowledge, all knowledge subtests, Fear, and Overall Attitudes. Statistical significance was also located on Total Knowledge, Pathology and Transmission knowledge subtests, and Sensitivity, as well as between Pathology and Instruction, and General Statements and Facts and Communication.^ The only variable determined to have statistical significance on both knowledge and attitudes was classroom AIDS instruction. Participants with previous AIDS instruction showed greater knowledge and possessed more positive attitudes. A review of previous research indicated training to be effective in increasing knowledge and fostering more favorable behavior toward persons with AIDS. Therefore, this study finds AIDS training to be beneficial for all teachers and is recommended during preservice education or through inservices for teachers already in the field. ^

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The present research evidences a field setting studying attitudinal and behavioral results of five Black group contacts. The research was designed, in part, to determine the demographic, cultural, social, and psychological factors associated with intrablack perceptions of conflict and work attitudes in an African American organization. Two organizational groups, African Americans and Caribbean/West Indians totaling 112 participants were studied. The objective of the research was to gain information about attitudinal levels perceived by each of the two groups. Each group rated the other group on items dealing with conflict and work attitudes. One-way analysis of variances (ANOVAs) were employed to test the overall differences on scale means among the groups. The findings in this study buttress some of the major themes in the impressionistic literature on cultural/multicultural diversity in organizations and Caribbean/West Indian literature. The data are reported and examined, and theoretical implications are discussed. ^

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This study examined the feasibility of using a session impact measure with a sample of 24 at risk high school students participating in an intervention targeting identity and intimacy. Three therapists led 3 intervention groups with the same format. The study investigated the impact of therapy process, including Group, Facilitator, Skills, and Exploration impacts as measured by the Session Evaluation Form (SEF). The study also investigated the differential impact of session process on intervention outcome as measured by the CPSS, EPSI, RAVS, EIPQ and Youth Report Form. Analyses were conducted using descriptive statistics, frequencies, one-way analysis of variance (ANOVA), and Chi square tests. The results supported the utility of the SEF and they tentatively supported the impact of the therapist on participants' perceptions of therapeutic processes and on intervention outcome. In particular, Group 1 performed better than Group 3. This study found that the SEF is a useful session impact measure. ^

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Current views of the nature of knowledge and of learning suggest that instructional approaches in science education pay closer attention to how students learn rather than on teaching. This study examined the use of approaches to teaching science based on two contrasting perspectives in learning, social constructivist and traditional, and the effects they have on students' attitudes and achievement. Four categories of attitudes were measured using the Upper Secondary Attitude Questionnaire: Attitude towards school, towards the importance of science, towards science as a career, and towards science as a subject in school. Achievement was measured by average class grades and also with a researcher/teacher constructed 30-item test that involved three sub-scales of items based on knowledge, and applications involving near-transfer and far-transfer of concepts. The sample consisted of 202 students in nine intact classrooms in chemistry at a large high school in Miami, Florida, and involved two teachers. Results were analyzed using a two-way analysis of covariance (ANCOVA) with a pretest in attitude as the covariate for attitudes and prior achievement as the covariate for achievement. A comparison of the adjusted mean scores was made between the two groups and between females and males. ^ With constructivist-based teaching, students showed more favorable attitude towards science as a subject, obtained significantly higher scores in class achievement, total achievement and achievement on the knowledge sub-scale of the knowledge and application test. Students in the traditional group showed more favorable attitude towards school. Females showed significantly more positive attitude towards the importance of science and obtained significantly higher scores in class achievement. No significant interaction effects were obtained for method of instruction by gender. ^ This study lends some support to the view that constructivist-based approaches to teaching science is a viable alternative to traditional modes of teaching. It is suggested that in science education, more consideration be given to those aspects of classroom teaching that foster closer coordination between social influences and individual learning. ^

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The present study identified and compared Coronary Heart Disease (CHD) risk factors quantified as “CHD risk point standards” (CHDRPS) among tri-ethnic (White non-Hispanic [WNH], Hispanic [H], and Black non-Hispanic [BNH]) college students. All 300 tri-ethnic subjects completed the Cardiovascular Risk Assessment Instruments and had blood pressure readings recorded on three occasions. The Bioelectrical Impedance Analysis (BIA) was used to measure body composition. Students' knowledge of CHD risk factors was also measured. In addition, a 15 ml fasting blood sample was collected from 180 subjects and blood lipids and Homocysteine (tHcy) levels were measured. Data were analyzed by gender and ethnicity using one-way Analysis of Variance (ANOVA) with Bonferroni's pairwise mean comparison procedure, Pearson correlation, and Chi-square test with follow-up Bonferroni's Chi-square tests. ^ The mean score of CHDRPS for all subjects was 19.15 ± 6.79. Assigned to the CHD risk category, college students were below-average risk of developing CHD. Males scored significantly (p < 0.013) higher for CHD risk than females, and BNHs scored significantly (p < 0.033) higher than WNHs. High consumption of dietary fat saturated fat and cholesterol resulted in a high CHDRPS among H males and females and WNH females. High alcohol consumption resulted in a high CHDRPS among all subjects. Mean tHcy ± SD of all subjects was 6.33 ± 3. 15 μmol/L. Males had significantly (p < 0.001) higher tHcy than females. Black non-Hispanic females and H females had significantly (p < 0.003) lower tHcy than WNH females. Positive associations were found between tHcy levels and CHDRPS among females (p < 0.001), Hs (p < 0.001), H males (p < 0.049), H females (p < 0.009), and BNH females (p < 0.005). Significant positive correlations were found between BMI levels and CHDRPS in males (p < 0.001), females (p < 0.001), WNHs (p < 0.008), Hs (p < 0.001), WNH males (p < 0.024), H males (p < 0.004) and H females (p < 0.001). The mean knowledge of CHD questions of all subjects was 71.70 ± 7.92 out of 100. The mean knowledge of CHD was significantly higher for WNH males (p < 0.039) than BNH males. A significant inverse correlation (r = 0.392, p < 0.032) was found between the CHD knowledge and CHDRPS in WNH females. The researcher's findings indicate strong gender and ethnic differences in CHD risk factors among the college-age population. ^

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This investigation studied the differences in learning styles among ethnically diverse secondary science students from a multicultural urban high school. It examined whether there were learning style differences among samples based on ethnicity, gender, academic grouping, and academic achievement. The learning style elements were based on scores of the Dunn, Dunn, and Price Learning Style Inventory (LSI) (1997). The sample (n = 476) consisted of students enrolled in Life Science courses. The analyses of data were made by one way analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA). ^ Significant differences were found among students for three of the four groups tested. The largest numbers of differences in learning style element preference were in academic grouping, with eight significant differences showing small or medium effect sizes. There were four significant differences between genders and one significant difference among ethnic groups. Effect size was small. The data analyses showed that individual differences have a much bigger effect than group differences on learning style, and that proportions in learning style element categories reveal more information than means of groups. ^ This study implied the need to increase awareness of differences in learning styles among students and help educators to understand them. Other predictors of learning styles might account for a large amount of the unexplained variation. Overall, this study reinforces the body of existing literature. ^

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The purpose of this research was to examine the relationship between teaching readiness and teaching excellence with three variables of preparedness of adjunct professors teaching career technical education courses through student surveys using a correlational design of two statistical techniques; least-squares regression and one-way analysis of variance. That is, the research tested the relationship between teacher readiness and teacher excellence with the number of years teaching, the number of years of experience in the professional field and exposure to teaching related professional development, referred to as variables of preparedness.^ The results of the research provided insight to the relationship between the variables of preparedness and student assessment of their adjunct professors. Concerning the years of teaching experience, this research found a negative inverse relationship with how students rated their professors' teaching readiness and excellence. The research also found no relationship between years of professional experience and the students' assessment. Lastly, the research found a significant positive relationship between the amount of teaching related professional development taken by an adjunct professor and the students' assessment in teaching readiness and excellence.^ This research suggests that policies and practices at colleges should address the professional development needs of adjunct professors. Also, to design a model that meets the practices of inclusion for adjunct faculty and to make professional development a priority within the organization. Lastly, implement that model over time to prepare adjuncts in readiness and excellence. ^

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This research was conducted in Chia-Yi, Taiwan to study the needs of adult education participants to determine the factors necessary to provide direction for the development of university adult education curriculum and supportive government educational policies. Factors researched were characteristics of the adult learner, theories of adult learning, demands of adult education, and implications of university adult education as the theoretical foundation for the development of specific curriculum development efforts. The study investigated adult learning needs and their relationship with demographic variable. Analyzing the needs of adult education participant and the relative factors through a survey resulted in recommendations for the development of adult education program plans, content of curriculum, and teaching. Research questions were analyzed using descriptive statistics, frequencies, chi square, one-way analysis of variance (ANOVA), and post hoc analysis. ^ The study showed that most participants in these adult education activities were under forty, middle class, of above average educational levels, and either living or working in the city. People who were older, of lesser social and economic positions, with lower educational standards, and living/working in the country, did not participate as much in adult education opportunities. Recommendations included that in the planning or setting up of adult education activities, attention be given to all the possible barriers or problems that are likely to occur in people's participation, e.g., motivation, interests, content of courses, teaching methods, willingness of participation, qualification of teachers, time, funds, locations, and so on. It is suggested that the resolution of these problems can significantly increase the participation of adult education. ^

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The purpose of this study was to explore the impact of the Florida State-mandated Basic Skills Exit Tests (BSET) on the effectiveness of remedial instruction programs to adequately serve the academically underprepared student population. The primary research question concerned whether the introduction of the BSET has resulted in remedial completers who are better prepared for college-level coursework. ^ This study consisted of an ex post facto research design to examine the impact of the BSET on student readiness for subsequent college-level coursework at Miami-Dade Community College. Two way analysis of variance was used to compare the performance of remedial and college-ready students before and after the introduction of the BSET requirement. Chi-square analysis was used to explore changes in the proportion of students completing and passing remedial courses. Finally, correlation analysis was used to explore the utility of the BSET in predicting subsequent college-level course performance. Differences based on subject area and race/ethnicity were explored. ^ The introduction of the BSET did not improve the performance of remedial completers in subsequent college-level courses in any of the subject areas. The BSET did have a negative impact on the success rate of students in remedial reading and mathematics courses. There was a significant decrease in minority students' likelihood of passing remedial reading and mathematics courses after the BSET was introduced. The reliability of the BSET is unacceptably low for all subject areas, based on estimates derived from administrations at M-DCC. Nevertheless, there was a significant positive relationship between BSET score and grade point average in subsequent college-level courses. This relationship varied by subject area and ethnicity, with the BSET reading score having no relationship with subsequent course performance for Black non-Hispanic students. ^ The BSET had no discernable positive effect on remedial student performance in subsequent college-level courses. In other words, the BSET has not enhanced the effectiveness of the remedial programs to prepare students for later coursework at M-DCC. The BSET had a negative impact on the progress and success of students in remedial reading and mathematics. ^

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The purpose of the study was to compare the English III success of students whose home language is Haitian Creole (SWHLIHC) with that of the more visible African American high school students in the Miami Dade County Public Schools System, in an effort to offer insight that might assist educators in facilitating the educational success of SWHLIHC in American Literature class.^ The study was guided by two important theories on how students interact with and learn from literature. They are Reader Response Theory which advocates giving students the opportunity to become involved in the literature experience (Rosenblatt, 1995), and Critical Literacy, a theory developed by Paolo Freire and Henry Giroux, which espouses a critical approach to analysis of society that enables people to analyze social problems through lenses that would reveal social inequities and assist in transforming society into a more equitable entity.^ Data for the study: 10th grade reading FCAT scores, English III/American Literature grades, and Promotion to English IV records for the school year 2010-2011 were retrieved from the records division of the Miami Dade County Public Schools System. The study used a quantitative methods approach, the central feature of which was an ex post facto design with hypotheses (Newman, Newman, Brown, & McNeely, 2006). The ex post facto design with hypotheses was chosen because the researcher postulated hypotheses about the relationships that might exist between the performances of SWHLIHC and those of African American students on the three above mentioned variables. This type of design supported the researcher's purpose of comparing these performances.^ One way analysis of variance (ANOVA), two way ANOVAs, and chi square tests were used to examine the two groups' performances on the 10th grade reading FCAT, their English III grades, and their promotion to English IV. ^ The study findings show that there was a significant difference in the performance of SWHLIHC and African American high school students on all three independent variables. SWHLIHC performed significantly higher on English III success and promotion to English IV. African American high school students performed significantly higher on the reading FCAT.^