Statistical analysis and optimal classification of blood cell populations using Gaussian distributions

This dissertation develops a new figure of merit to measure the similarity (or dissimilarity) of Gaussian distributions through a novel concept that relates the Fisher distance to the percentage of data overlap. The derivations are expanded to provide a generalized mathematical platform for determining an optimal separating boundary of Gaussian distributions in multiple dimensions. Real-world data used for implementation and in carrying out feasibility studies were provided by Beckman-Coulter. It is noted that although the data used is flow cytometric in nature, the mathematics are general in their derivation to include other types of data as long as their statistical behavior approximate Gaussian distributions. ^ Because this new figure of merit is heavily based on the statistical nature of the data, a new filtering technique is introduced to accommodate for the accumulation process involved with histogram data. When data is accumulated into a frequency histogram, the data is inherently smoothed in a linear fashion, since an averaging effect is taking place as the histogram is generated. This new filtering scheme addresses data that is accumulated in the uneven resolution of the channels of the frequency histogram. ^ The qualitative interpretation of flow cytometric data is currently a time consuming and imprecise method for evaluating histogram data. This method offers a broader spectrum of capabilities in the analysis of histograms, since the figure of merit derived in this dissertation integrates within its mathematics both a measure of similarity and the percentage of overlap between the distributions under analysis. ^

Statistical analysis and meta-analysis of microarray data

The microarray technology provides a high-throughput technique to study gene expression. Microarrays can help us diagnose different types of cancers, understand biological processes, assess host responses to drugs and pathogens, find markers for specific diseases, and much more. Microarray experiments generate large amounts of data. Thus, effective data processing and analysis are critical for making reliable inferences from the data. ^ The first part of dissertation addresses the problem of finding an optimal set of genes (biomarkers) to classify a set of samples as diseased or normal. Three statistical gene selection methods (GS, GS-NR, and GS-PCA) were developed to identify a set of genes that best differentiate between samples. A comparative study on different classification tools was performed and the best combinations of gene selection and classifiers for multi-class cancer classification were identified. For most of the benchmarking cancer data sets, the gene selection method proposed in this dissertation, GS, outperformed other gene selection methods. The classifiers based on Random Forests, neural network ensembles, and K-nearest neighbor (KNN) showed consistently god performance. A striking commonality among these classifiers is that they all use a committee-based approach, suggesting that ensemble classification methods are superior. ^ The same biological problem may be studied at different research labs and/or performed using different lab protocols or samples. In such situations, it is important to combine results from these efforts. The second part of the dissertation addresses the problem of pooling the results from different independent experiments to obtain improved results. Four statistical pooling techniques (Fisher inverse chi-square method, Logit method. Stouffer's Z transform method, and Liptak-Stouffer weighted Z-method) were investigated in this dissertation. These pooling techniques were applied to the problem of identifying cell cycle-regulated genes in two different yeast species. As a result, improved sets of cell cycle-regulated genes were identified. The last part of dissertation explores the effectiveness of wavelet data transforms for the task of clustering. Discrete wavelet transforms, with an appropriate choice of wavelet bases, were shown to be effective in producing clusters that were biologically more meaningful. ^

Shifting N and P limitation along a north-south gradient of mangrove estuaries in South Florida

A multivariate statistical analysis was applied to a 10 year, multiparameter data set in an effort to describe the spatial dependence and inherent variation of water quality patterns in the mangrove estuaries of Ten Thousand Islands – Whitewater Bay area. Principal component analysis (PCA) of 16 water quality parameters collected monthly resulted in five groupings, which explained 72.5% of the variance of the original variables. The “Organic” component (PCI) was composed of alkaline phosphatase activity, total organic nitrogen, and total organic carbon; the “Dissolved Inorganic N” component (PCII) contained NO 3 − , NO 2 − , and NH 4 + ; the “Phytoplankton” component (PCIII) was made up of total phosphorus, chlorophyll a, and turbidity; dissolved oxygen and temperature were inversely related (PCIV); and salinity and soluble reactive phosphorus made up PCV. A cluster analysis of the mean and SD of PC scores resulted in the spatial aggregation of the 47 fixed stations into six classes having similar water quality, which we defined as: Mangrove Rivers, Whitewater Bay, Gulf Islands, Coot Bay, Blackwater River, and Inland Waterway. Marked differences in physical, chemical, and biological characteristics among classes were illustrated by this technique. Comparison of medians and variability of parameters among classes allowed large scale generalizations as to underlying differences in water quality in these regions. A strong south to north gradient in estuaries from high N - low P to low N - high P was ascribed to marked differences in landuse, freshwater input, geomorphology, and sedimentary geology along this tract. The ecological significance of this gradient discussed along with potential effects of future restoration plans.

``This is your brain on drugs'': The public policy of anti -drug programming. An exploratory analysis of media and other sources of drug information for adolescents

In the 1980s, government agencies sought to utilize research on drug use prevention to design media campaigns. Enlisting the assistance of the national media, several campaigns were designed and initiated to bring anti-drug use messages to adolescents in the form of public service advertising. This research explores the sources of information selected by adolescents in grades 7 through 12 and how the selection of media and other sources of information relate to drug use behavior and attitudes and perceptions related to risk/harm and disapproval of friends' drug-using activities.^ Data collected from 1989 to 1992 in the Miami Coalition School Survey provided a random selection of secondary school studies. The responses of these students were analyzed using multivariate statistical techniques.^ Although many of the students selected media as the source for most of their information on the effects of drugs on the people who use them, the selection of media was found to be positively related to alcohol use and negatively related to marijuana use. The selection of friends, brothers, or sisters was a statistically significant source for adolescents who smoke cigarettes, use alcohol or marijuana.^ The results indicate that the anti-drug use messages received by students may be canceled out by media messages perceived to advocate substance use and that a more persuasive source of information for adolescents may be friends and siblings. As federal reports suggest that the economic costs of drug abuse will reach an estimated $150 billion by 1997 if current trends continue, prevention policy that addresses the glamorization of substance use remains a national priority. Additionally, programs that advocate prevention within the peer cluster must be supported, as peers are an influential source for both inspiring and possibly preventing drug use behavior. ^

GIS-integrated mathematical modeling of social phenomena at macro- and micro- levels—a multivariate geographically-weighted regression model for identifying locations vulnerable to hosting terrorist safe-houses: France as case study

Adaptability and invisibility are hallmarks of modern terrorism, and keeping pace with its dynamic nature presents a serious challenge for societies throughout the world. Innovations in computer science have incorporated applied mathematics to develop a wide array of predictive models to support the variety of approaches to counterterrorism. Predictive models are usually designed to forecast the location of attacks. Although this may protect individual structures or locations, it does not reduce the threat—it merely changes the target. While predictive models dedicated to events or social relationships receive much attention where the mathematical and social science communities intersect, models dedicated to terrorist locations such as safe-houses (rather than their targets or training sites) are rare and possibly nonexistent. At the time of this research, there were no publically available models designed to predict locations where violent extremists are likely to reside. This research uses France as a case study to present a complex systems model that incorporates multiple quantitative, qualitative and geospatial variables that differ in terms of scale, weight, and type. Though many of these variables are recognized by specialists in security studies, there remains controversy with respect to their relative importance, degree of interaction, and interdependence. Additionally, some of the variables proposed in this research are not generally recognized as drivers, yet they warrant examination based on their potential role within a complex system. This research tested multiple regression models and determined that geographically-weighted regression analysis produced the most accurate result to accommodate non-stationary coefficient behavior, demonstrating that geographic variables are critical to understanding and predicting the phenomenon of terrorism. This dissertation presents a flexible prototypical model that can be refined and applied to other regions to inform stakeholders such as policy-makers and law enforcement in their efforts to improve national security and enhance quality-of-life.

Perceptions of beginning teachers in Florida regarding their preparation as it relates to the Florida Essential Generic Competencies

The purpose of the study is to investigate how beginning teachers in the state of Florida perceive their preparation to demonstrate the 27 Florida Essential Generic Competencies.^ The basic research question of this study was: How do beginning teachers perceive their level of preparation regarding their implementation of the Florida Essential Generic Competencies? This study identified and categorized the perceived degree of preparation for each of the competencies. Also, elementary, middle, and high school beginning teachers were compared to find significant differences and similarities in their perception of their preparation. A comparison was also done for graduates from in-state versus out-of-state and private versus public institutions.^ A survey developed in collaboration with the Department of Education, Florida State University, members of the Professional Orientation Program (POP) Coordinators, and the Project Director of Program Review in the College of Education at the University of South Florida, was sent to 5,076 beginning teachers. A total of 1,995 returned the survey in February of 1993. The Multivariate Analysis of Variance (MANOVA) procedure was used (Alpha =.05). Statistical analysis of the data involved a comparison of the different groups of beginning teachers by school level and kind of graduating institutions. The dependent variables analyzed were the responses to all items representing the generic competencies.^ The study identified and categorized the degree of preparation for each competency. The competencies receiving the lowest ratings for degree of preparation were: integrate computers in instruction; manage situations involving child abuse and/or neglect; severe emotional stress; alcohol and drug abuse.^ The Wilkes lambda and the Hotellings multivariate tests of significance were used to examine the differences among the groups. The competency items were further analyzed by a univariate F test. Results indicated that: (1) significant differences were found in nine competency items in which elementary teachers felt better prepared than middle and high school beginning teachers, (2) graduates from a Florida teacher education program felt they were better prepared in demonstrating the competencies than those from out-of-state schools, and (3) no significant difference was found in the perceptions of those who graduated from public versus private institutions.^ Based on the findings of this study, the following recommendations are made: (1) Florida's institutions responsible for teacher preparation programs need to focus on those competencies receiving the lowest ratings, (2) Districts should provide an orientation program for out-of-state beginning teachers, and (3) The survey instrument should be used annually to evaluate teacher education programs. ^

The effects of the outdoor experiential ropes course on perceived team performance

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). ^

Marketing practices and their effectiveness in Taiwan's colleges of technology

The main purpose of this study was to investigate marketing practices in Taiwan's institutions of higher education and their relationship with students' college choice behaviors and attitudes. The study was conducted in 11 Taiwan's colleges of technology. It employed a multistrand conversion mixed model design, consisting of a qualitative and a quantitative strand. Funnel-sequenced interviews were conducted with 19 college administrators and the results were content analyzed using a constant-comparative method. The administrator interview data were also quantitized and used in cluster analysis of the institutions. Questionnaire data were collected from 1474 freshmen students, and analyzed using several univariate and multivariate statistical techniques including factor analysis, MANOVA, and correspondence analysis. ^ Analyses indicated that a weak relationship existed between institutions' marketing intensity and students' college choice. Students did not consider institutions' recruitment activities useful in their college searching process. They also reported little knowledge of their current school when they were deciding to enroll. Data analysis also revealed that students were practically oriented in their college selection. Academic resources, employability after graduation, and tuition were the most important attributes in students' college selection. Parents and students' social network such as friends and high school teachers were significant personal sources in enrollment decisions while institutions' representatives (i.e., recruiters) were considered the least influential. ^ Using cluster analysis, institutions were divided into three groups based on intensity of marketing efforts. Multivariate analysis of variance did not reveal significant differences between the college choice behaviors and attitudes of students who entered these three types of institutions. ^ Content analysis of the administrators' interviews indicated that the majority of them practiced passive marketing. This was primarily as a result of resistance to active marketing, lack of leadership commitment, insufficient financial and human resources, little faculty involvement, and inexperience in marketing. In comparison to public institutions, private institutions showed a more favorable attitude towards marketing concepts. They were well advanced in their recruitment activities while public schools were relatively hesitant to use marketing. Curriculum issues were not well represented in marketing activities and did not seem to be impacted by marketing needs. Based on the analysis of qualitative and quantitative data, it can be concluded that in these colleges, curriculum was more driven by commercial and industrial interest than by students' demands. ^ Theoretical, policy, and methodological implementation of the results were discussed. ^

Perceptions regarding intercollegiate alliance among administrators of Taiwanese technological higher education institutions

This study explored Taiwanese technological higher education administrators' perceptions about the motivation and capability of their institutions to form intercollegiate alliance, their preferred areas of collaboration, and their preferred partner attributes. Possible differences in perceptions of administrators from public and private institutions were also explored. ^ The study targeted six chief administrators in each of 88 technological and vocational higher education institutions in Taiwan. A mix of quantitative and qualitative research designs was used to collect and analyze data. Quantitative data were collected from 328 administrators through a questionnaire and analyzed using univariate and multivariate statistical techniques. In addition, to obtain a deeper understanding of the process of alliance formation, qualitative data were collected through interviews with 13 administrators and content analyzed using emergent themes analysis. ^ Findings revealed that Taiwanese technological education administrators were not strongly confident in the competitive positions of their institutions. They perceived themselves as non-competitive in faculty research performance, in getting financial support, and having easy-access locations. Administrators believed that forming an alliance would help them obtain more external resources, achieve academic enhancement, provide better services, have a stronger voice, and obtain promotion to a higher institutional level. Cost cutting was not believed to be an attainable goal. ^ Strong interest was expressed for an alliance in the sharing of technology, information networks, and library resources; cross-registration; admissions and recruitment practices; school-industry endeavors; and international academic exchanges. Sharing of administrators and staff, joint bidding and purchasing, and cooperative fundraising were considered of less interest. ^ Administrators favored partners who have excellent academic programs, who have complementary skills, who are willing to share resources, and who are enthusiastic leaders. They also wanted partners to match their institutions in performance and prestige and to be geographically close to them. ^ Multivariate analysis of variance did not reveal significant differences between the perceptions of the administrators from public and private institutions. It was concluded that despite governmental encouragement and the institutions' eagerness for forming an alliance, the administrators had little confidence that a sustainable alliance could be arranged. ^

Substance use and sexual risk behaviors among adolescent detainees

There is a commonly presumed link among sexual risk behavior, substance use, and other psychosocial factors among adolescents. However, these relationships have been relatively understudied in detained, low-income, minority, substance abusing adolescents. This study addresses this gap in the literature with a secondary data analysis based on a sample of adolescent offenders in two detention and treatment centers in Miami-Dade County. Univariate, bivariate statistical analysis and multivariate logistic regressions were conducted on baseline data from structured interviews with 455 adolescents participating in an NIH funded prevention intervention. Data were analyzed to assess relationships among self-reported substance use, STD history, HIV/AIDS knowledge, condom use, condom use attitudes, and skills, peer and parental approval to use condoms, and race/ethnicity. The adolescent sample was 74.1% male, and 25.9% female and 35.4% African American, 25.1% non-African American Latino, 11.2% White, and 28.4% of other race/ethnicity categories. The mean age was 15.6 years. Results suggested that alcohol use (p < 0.001) and use of marijuana, cocaine and other drugs (p < 0.001) are significant variables when explaining the variability in sexual risk behaviors. Results also suggested that unprotected vaginal, anal, and oral sex increased with higher alcohol and drug use (p < 0.001) and that positive attitudes about personally using condoms (p < 0.001) were also significantly related to condom use. Logistic regressions showed that race/ethnicity was a significant control variable when explaining the variability of condom use. Being White and Latino were significantly associated with less condom use during oral and anal sex when compared to other racial/ethnic groups. These results indicated that risky sexual behavior and HIV infection risk are significantly associated with substance use, particularly alcohol use. Therefore, proper screening and identification of alcohol use, and condom use attitudes could maximize the efficacy of referrals to programs targeting both issues and increase the potential for appropriate primary and secondary prevention and treatment among adolescent detainees.

Reliability analysis of encapsulation methods for lead -based paint through an accelerated life testing

The adverse health effects of long-term exposure to lead are well established, with major uptake into the human body occurring mainly through oral ingestion by young children. Lead-based paint was frequently used in homes built before 1978, particularly in inner-city areas. Minority populations experience the effects of lead poisoning disproportionately. ^ Lead-based paint abatement is costly. In the United States, residents of about 400,000 homes, occupied by 900,000 young children, lack the means to correct lead-based paint hazards. The magnitude of this problem demands research on affordable methods of hazard control. One method is encapsulation, defined as any covering or coating that acts as a permanent barrier between the lead-based paint surface and the environment. ^ Two encapsulants were tested for reliability and effective life span through an accelerated lifetime experiment that applied stresses exceeding those encountered under normal use conditions. The resulting time-to-failure data were used to extrapolate the failure time under conditions of normal use. Statistical analysis and models of the test data allow forecasting of long-term reliability relative to the 20-year encapsulation requirement. Typical housing material specimens simulating walls and doors coated with lead-based paint were overstressed before encapsulation. A second, un-aged set was also tested. Specimens were monitored after the stress test with a surface chemical testing pad to identify the presence of lead breaking through the encapsulant. ^ Graphical analysis proposed by Shapiro and Meeker and the general log-linear model developed by Cox were used to obtain results. Findings for the 80% reliability time to failure varied, with close to 21 years of life under normal use conditions for encapsulant A. The application of product A on the aged gypsum and aged wood substrates yielded slightly lower times. Encapsulant B had an 80% reliable life of 19.78 years. ^ This study reveals that encapsulation technologies can offer safe and effective control of lead-based paint hazards and may be less expensive than other options. The U.S. Department of Health and Human Services and the CDC are committed to eliminating childhood lead poisoning by 2010. This ambitious target is feasible, provided there is an efficient application of innovative technology, a goal to which this study aims to contribute. ^

Perceptions of beginning teachers in Florida regarding their preparation as it relates to the Florida essential generic competencies

The purpose of the study is to investigate how beginning teachers in the state of Florida perceive their preparation to demonstrate the 27 Florida Essential Generic Competencies. The basic research question of this study was: How do beginning teachers perceive their level of preparation regarding their implementation of the Florida Essential Generic Competencies? This study identified and categorized the perceived degree of preparation for each of the competencies. Also, elementary, middle, and high school beginning teachers were compared to find significant differences and similarities in their perception of their preparation. A comparison was also done for graduates from in-state versus out-of-state and private versus public institutions. A survey developed in collaboration with the Department of Education, Florida State University, members of the Professional Orientation Program (POP) Coordinators, and the Project Director of Program Review in the College of Education at the University of South Florida, was sent to 5,076 beginning teachers. A total of 1,995 returned the survey in February of 1993. The Multivariate Analysis of Variance (MANOVA) procedure was used (Alpha = .05). Statistical analysis of the data involved a comparison of the different groups of beginning teachers by school level and kind of graduating institutions. The dependent variables analyzed were the responses to all items representing the generic competencies. The study identified and categorized the degree of preparation for each competency. The competencies receiving the lowest ratings for degree of preparation were: integrate computers in instruction; manage situations involving child abuse and/or neglect; severe emotional stress; alcohol and drug abuse. The Wilkes lambda and the Hotellings multivariate tests of significance were used to examine the differences among the groups. The competency items were further analyzed by a univariate F test. Results indicated that: (1) significant differences were found in nine competency items in which elementary teachers felt better prepared than middle and high school beginning teachers, (2) graduates from a Florida teacher education program felt they were better prepared in demonstrating the competencies than those from out-of-state schools, and (3) no significant difference was found in the perceptions of those who graduated from public versus private institutions. Based on the findings of this study, the following recommendations are made: (1) Florida's institutions responsible for teacher preparation programs need to focus on those competencies receiving the lowest ratings, (2) Districts should provide an orientation program for out-of-state beginning teachers, and (3) The survey instrument should be used annually to evaluate teacher education programs.