Development of safety performance functions for empirical Bayes estimation of crash reduction factors

Crash reduction factors (CRFs) are used to estimate the potential number of traffic crashes expected to be prevented from investment in safety improvement projects. The method used to develop CRFs in Florida has been based on the commonly used before-and-after approach. This approach suffers from a widely recognized problem known as regression-to-the-mean (RTM). The Empirical Bayes (EB) method has been introduced as a means to addressing the RTM problem. This method requires the information from both the treatment and reference sites in order to predict the expected number of crashes had the safety improvement projects at the treatment sites not been implemented. The information from the reference sites is estimated from a safety performance function (SPF), which is a mathematical relationship that links crashes to traffic exposure. The objective of this dissertation was to develop the SPFs for different functional classes of the Florida State Highway System. Crash data from years 2001 through 2003 along with traffic and geometric data were used in the SPF model development. SPFs for both rural and urban roadway categories were developed. The modeling data used were based on one-mile segments that contain homogeneous traffic and geometric conditions within each segment. Segments involving intersections were excluded. The scatter plots of data show that the relationships between crashes and traffic exposure are nonlinear, that crashes increase with traffic exposure in an increasing rate. Four regression models, namely, Poisson (PRM), Negative Binomial (NBRM), zero-inflated Poisson (ZIP), and zero-inflated Negative Binomial (ZINB), were fitted to the one-mile segment records for individual roadway categories. The best model was selected for each category based on a combination of the Likelihood Ratio test, the Vuong statistical test, and the Akaike's Information Criterion (AIC). The NBRM model was found to be appropriate for only one category and the ZINB model was found to be more appropriate for six other categories. The overall results show that the Negative Binomial distribution model generally provides a better fit for the data than the Poisson distribution model. In addition, the ZINB model was found to give the best fit when the count data exhibit excess zeros and over-dispersion for most of the roadway categories. While model validation shows that most data points fall within the 95% prediction intervals of the models developed, the Pearson goodness-of-fit measure does not show statistical significance. This is expected as traffic volume is only one of the many factors contributing to the overall crash experience, and that the SPFs are to be applied in conjunction with Accident Modification Factors (AMFs) to further account for the safety impacts of major geometric features before arriving at the final crash prediction. However, with improved traffic and crash data quality, the crash prediction power of SPF models may be further improved.

Team Primacy Concept-based employee evaluation and job performance

This qualitative case study explored how employees learn from Team Primacy Concept (TPC)-based employee evaluation and how they apply the knowledge in their job performance. Kolb's experiential learning model (1974) served as a conceptual framework for the study to reveal the process of how employees learn from TPC evaluation, namely, how they experience, reflect, conceptualize and act on performance feedback. TPC based evaluation is a form of multirater evaluation that consists of three components: self-feedback, supervisor's feedback, and peer feedback. The distinctive characteristic of TPC based evaluation is the team evaluation component during which the employee's professional performance is discussed by one's peers in a face-to-face team setting, while other forms of multirater evaluation are usually conducted in a confidential and anonymous manner.^ Case study formed the methodological framework. The case was the Southeastern Virginia (SEVA) region of the Institute for Family Centered Services, and the participants were eight employees of the SEVA region. Findings showed that the evaluation process was anxiety producing for employees, especially the process of peer evaluation in a team setting. Preparation was found to be an important phase of TPC evaluation. Overall, the positive feedback delivered in a team setting made team members feel acknowledged. The study participants felt that honesty in providing feedback and openness to hearing challenges were significant prerequisites to the TPC evaluation process. Further, in the planning phase, employees strove to develop goals for themselves that were meaningful. Also, the catalyst for feedback implementation appeared to stem from one's accountability to self and to the client or community. Generally, the participants identified a number of performance improvement goals that they attained during their employment with IFCS, which were supported by their developmental plans.^ In conclusion, the study identified the process by which employees learned from TPC-based employee evaluation and the ways in which they used the knowledge to improve their job performance. Specifically, the study examined how participants felt and what they thought about TPC-based feedback, in what ways they reflected and made meaning of the feedback, and how they used the feedback to improve their job performance.^

Essays on firm behavior and firm performance

This dissertation comprises three individual chapters in an effort to examine different explanatory variables that affect firm performance. Chapter Two proposes an additional determinant of firm survival. Based on a detailed examination of firm survival in the British automobile industry between 1895 and 1970, we conclude that a firm's selection of submarket (defined by quality level) influenced survival. In contrast to findings for the US automobile industry, there is no evidence of first-mover advantage in the market as a whole. However, we do find evidence of first-mover advantage after conditioning on submarket choice. Chapter Three examines the effects of product line expansion on firm performance in terms of survival time. Based on a detailed examination of firm survival time in the British automobile industry between 1895 and 1970, we find that diversification exerts a positive effect on firm survival. Furthermore, our findings support the literature with respect to the impacts of submarket types, pre-entry experience, and timing of entry on firm survival time. Chapter Four examines corporate diversification in U.S. manufacturing and service firms. We develop measures of how related a firm's diverse activities are using input-output data and the NAILS classification to construct indexes of "vertical relatedness" and "complementarity". Strong relationships between these two measures are found. We utilize profitability and excess value as the measure for firm performance. Econometric analysis reveals that there is no relationship between the degree of relatedness of diversification and firm performance for the study period.

A method for enhancing digital information displayed to computer users with visual refractive errors via spatial and spectral processing

This research pursued the conceptualization, implementation, and verification of a system that enhances digital information displayed on an LCD panel to users with visual refractive errors. The target user groups for this system are individuals who have moderate to severe visual aberrations for which conventional means of compensation, such as glasses or contact lenses, does not improve their vision. This research is based on a priori knowledge of the user's visual aberration, as measured by a wavefront analyzer. With this information it is possible to generate images that, when displayed to this user, will counteract his/her visual aberration. The method described in this dissertation advances the development of techniques for providing such compensation by integrating spatial information in the image as a means to eliminate some of the shortcomings inherent in using display devices such as monitors or LCD panels. Additionally, physiological considerations are discussed and integrated into the method for providing said compensation. In order to provide a realistic sense of the performance of the methods described, they were tested by mathematical simulation in software, as well as by using a single-lens high resolution CCD camera that models an aberrated eye, and finally with human subjects having various forms of visual aberrations. Experiments were conducted on these systems and the data collected from these experiments was evaluated using statistical analysis. The experimental results revealed that the pre-compensation method resulted in a statistically significant improvement in vision for all of the systems. Although significant, the improvement was not as large as expected for the human subject tests. Further analysis suggest that even under the controlled conditions employed for testing with human subjects, the characterization of the eye may be changing. This would require real-time monitoring of relevant variables (e.g. pupil diameter) and continuous adjustment in the pre-compensation process to yield maximum viewing enhancement.

Performance of FRP-concrete bridges under blast loading

Catastrophic failure from intentional terrorist attacks on surface transportation infrastructure could he detrimental to the society. In order to minimize the vulnerabilities and to ensure a safe transportation system, the issue of security for transportation structures, primarily bridges, which are subjected to man-made hazards is investigated in this study. A procedure for identifying and prioritizing "critical bridges" using a screening and prioritization processes is established. For each of the "critical" bridges, a systematic risk-based assessment approach is proposed that takes into account the combination of threat occurrence likelihood, its consequences, and the socioeconomic importance of the bridge. A series of effective security countermeasures are compiled in the four categories of deterrence, detection, defense and mitigation to help reduce the vulnerability of critical bridges. The concepts of simplified equivalent I-shape cross section and virtual materials are proposed for integration into a nonlinear finite element model, which helps assess the performance of reinforced concrete structures with and without composite retrofit or hardening measures under blast loading. A series of parametric studies are conducted for single column and two-column pier frame systems as well as for an entire bridge. The parameters considered include column height, column type, concrete strength, longitudinal steel reinforcement ratio, thickness, fiber angle and tensile strength of the fiber reinforced polymer (FRP) tube, shape of the cross section, damping ratio and different bomb sizes. The study shows the benefits of hardening with composites against blast loading. The effect of steel reinforcement on blast resistance of the structure is more significant than the effect of concrete compressive strength. Moreover, multiple blasts do not necessarily lead to a more severe destruction than a single detonation at a strategically vulnerable location on the bridges.

The impact of bandwidth in structured interviewing and criterion stability in predicting and assessing manager performance across transition and maintenance stages

The current study examined the role of three important components in the use of structured employment interviewing in performance prediction: construct bandwidth, observed communication skill, and the stability/dynamicity of performance criteria over time. A matched sample of 242 hospitality managers was derived from a field data set provided by a large hospitality management organization. Interview data and two years of performance appraisal data were provided. Bandwidth analysis demonstrated only minimal differences in prediction between matched predictor-criterion pairs compared with predictor to overall aggregate ratings (unmatched). The communication skill analysis revealed that this interviewer rated observation significantly predicted a number of the individual performance dimensions as well as overall performance over time. Of the five interview items, the strongest overall predictor of performance was interviewer rated communication skill. The stability/dynamicity analyses demonstrated the performance criteria to be generally stable over the two year period examined, which provides support for the long held notion that performance criteria is stabile over time. However, there were two exceptions. The interview dimension customer service orientation had shifting relationships over time with four of the criteria over the two year period. The performance criteria employee development also demonstrated some instability in its relationships with predictors. Thus, some evidence of dynamicity in performance criteria was revealed. Interestingly, both of the most noteworthy findings in the study involved items that were rated differently than the others in the study. The rated interview item communication skill and the rated performance criteria client satisfaction were ratings that involved a more direct level of observation. Additional analyses also revealed evidence of a general factor of performance. These two themes are more fully covered in the discussion.

Adolescent readers' self-perceptions of affective factors related to performance on standardized tests

The purpose of this study was to investigate which affective factors of adolescent high school readers were related to high-level readers, middle-level readers and low-level readers. The research problem was to determine the relationship between adolescent high school students' self-perceived reading self-efficacy factors and the students' reading performance on a standardized reading assessment considering demographic factors of age, gender and socio-economic status as covariates. The research design was ex post facto making inferences without direct intervention. The sample was obtained from one large, diverse, urban high school, consisting of 9th and 10th grade adolescent students (N = 176). Students voluntarily completed a self-report, reading self-efficacy survey. School records were used to obtain standardized reading level scores, age, gender, and socio-economic status data. An exploratory factor analysis of the self-efficacy survey responses resulted in the identification of 7 underlying factors. The striving (low-level) readers had significantly lower self-perceptions on 5 of the 7 affective factors than the middle-level readers, and strong (high-level) readers, p < .05. The 5 affective factors on which the striving readers had significantly lower self-perceptions were: (a) Observational Comparison, (b) Progress, (c) Lack of Progress, (d) Lack of Anxiety, and (e) Positive Social Feedback. The 2 affective factors which were not significantly different for reader level were Anxiety and Negative Social Feedback. Girls had significantly less anxiety than boys for both of the factors in the Anxiety category. Statistical results showed that none of the demographic covariates tested; age, gender, or socio-economic status, moderated the relationship between affective reader self-efficacy factors and reader level. This study concluded that there were distinguishable differences for striving, middle, and strong readers' self-efficacy factors. Determining affective factors related to reading can be used to create better instructional environments and instruction for adolescent students.

A comparative analysis of self-determined evaluations of work performance and support needs by adults with mental retardation in supported work and in sheltered workshop environments

The purpose of this study was to determine if there was a difference in the self-determined evaluations of work performance and support needs by adults with mental retardation in supported employment and in sheltered workshop environments. The instrument, Job Observation and Behavior Scale: Opportunity for Self-Determination (JOBS: OSD; Brady, Rosenberg, & Frain, 2006), was administered to 38 adults with mental retardation from sheltered workshops and 32 adults with mental retardation from supported employment environments. Cross-tabulations with Chi-square tests and independent samples t-tests were conducted to evaluate differences between the two groups, sheltered workshop and supported work. Two Multivariate Analyses of Variance (MANOVAs) were conducted to determine the effect of work environment on Quality of Performance (QP) and Types of Support (TS) test scores and their subscales. ^ This study found that there were significant differences between the groups on the QP Behavior and Job Duties subscales. The sheltered workshop group perceived themselves as performing significantly better on job duties than the supported work group. Conversely, the supported work group perceived themselves to have better behavior than the sheltered workshop group. However, there were no significant differences between groups in their perception of support needs for the three subscales. ^ The findings imply that work environment affects the self-determined evaluations of work performance by adults with mental retardation. Recommendations for further study include (a) detailing the characteristics of supported work and sheltered workshops that support and/or discourage self-determined behaviors, (b) exploring the behavior of adults with mental retardation in sheltered workshops and supported work environments, and (c) analysis of the support needs for and understanding of them by adults with mental retardation in sheltered workshops and in supported work environments. ^

Effect of performance feedback on perceived knowledge and likelihood to pursue continuing education

The purpose of this study was to assess the effect of performance feedback on Athletic Trainers’ (ATs) perceived knowledge (PK) and likelihood to pursue continuing education (CE). The investigation was grounded in the theories of “the definition of the situation” (Thomas & Thomas, 1928) and the “illusion of knowing,” (Glenberg, Wilkinson, & Epstein, 1982) suggesting that PK drives behavior. This investigation measured the degree to which knowledge gap predicted CE seeking behavior by providing performance feedback designed to change PK. A pre-test post-test control-group design was used to measure PK and likelihood to pursue CE before and after assessing actual knowledge. ATs (n=103) were randomly sampled and assigned to two groups, with and without performance feedback. Two independent samples t-tests were used to compare groups on the difference scores of the dependent variables. Likelihood to pursue CE was predicted by three variables using multiple linear regression: perceived knowledge, pre-test likelihood to pursue CE, and knowledge gap. There was a 68.4% significant difference (t101=2.72, p=0.01, ES=0.45) between groups in the change scores for likelihood to pursue CE because of the performance feedback (Experimental group=13.7% increase; Control group=4.3% increase). The strongest relationship among the dependent variables was between pre-test and post-test measures of likelihood to pursue CE (F2,102=56.80, p<0.01, r=0.73, R2=0.53). The pre- and post-test predictive relationship was enhanced when group was included in the model. In this model [YCEpost=0.76XCEpre-0.34 Xgroup+2.24+E], group accounted for a significant amount of unique variance in predicting CE while the pre-test likelihood to pursue CE variable was held constant (F3,102=40.28, p<0.01, r=0.74, R2=0.55). Pre-test knowledge gap, regardless of group allocation, was a linear predictor of the likelihood to pursue CE (F1,102=10.90, p=.01, r=.31, R2=.10). In this investigation, performance feedback significantly increased participants’ likelihood to pursue CE. Pre-test knowledge gap was a significant predictor of likelihood to pursue CE, regardless if performance feedback was provided. ATs may have self-assessed and engaged in internal feedback as a result of their test-taking experience. These findings indicate that feedback, both internal and external, may be necessary to trigger CE seeking behavior.

Seismic performance of hybrid fiber reinforced polymer-concrete pier frame systems

As an alternative to transverse spiral or hoop steel reinforcement, fiber reinforced polymers (FRPs) were introduced to the construction industry in the 1980’s. The concept of concrete-filled FRP tube (CFFT) has raised great interest amongst researchers in the last decade. FRP tube can act as a pour form, protective jacket, and shear and flexural reinforcement for concrete. However, seismic performance of CFFT bridge substructure has not yet been fully investigated. Experimental work in this study included four two-column bent tests, several component tests and coupon tests. Four 1/6-scale bridge pier frames, consisting of a control reinforced concrete frame (RCF), glass FRP-concrete frame (GFF), carbon FRP-concrete frame (CFF), and hybrid glass/carbon FRP-concrete frame (HFF) were tested under reverse cyclic lateral loading with constant axial loads. Specimen GFF did not show any sign of cracking at a drift ratio as high as 15% with considerable loading capacity, whereas Specimen CFF showed that lowest ductility with similar load capacity as in Specimen GFF. FRP-concrete columns and pier cap beams were then cut from the pier frame specimens, and were tested again in three point flexure under monotonic loading with no axial load. The tests indicated that bonding between FRP and concrete and yielding of steel both affect the flexural strength and ductility of the components. The coupon tests were carried out to establish the tensile strength and elastic modulus of each FRP tube and the FRP mold for the pier cap beam in the two principle directions of loading. A nonlinear analytical model was developed to predict the load-deflection responses of the pier frames. The model was validated against test results. Subsequently, a parametric study was conducted with variables such as frame height to span ratio, steel reinforcement ratio, FRP tube thickness, axial force, and compressive strength of concrete. A typical bridge was also simulated under three different ground acceleration records and damping ratios. Based on the analytical damage index, the RCF bridge was most severely damaged, whereas the GFF bridge only suffered minor repairable damages. Damping ratio was shown to have a pronounced effect on FRP-concrete bridges, just the same as in conventional bridges. This research was part of a multi-university project, which is founded by the National Science Foundation (NSF) - Network for Earthquake Engineering Simulation Research (NEESR) program.

A capability maturity model to assess supply chain performance

In an overcapacity world, where the customers can choose from many similar products to satisfy their needs, enterprises are looking for new approaches and tools that can help them not only to maintain, but also to increase their competitive edge. Innovation, flexibility, quality, and service excellence are required to, at the very least, survive the on-going transition that industry is experiencing from mass production to mass customization. In order to help these enterprises, this research develops a Supply Chain Capability Maturity Model named S(CM)2. The Supply Chain Capability Maturity Model is intended to model, analyze, and improve the supply chain management operations of an enterprise. The Supply Chain Capability Maturity Model provides a clear roadmap for enterprise improvement, covering multiple views and abstraction levels of the supply chain, and provides tools to aid the firm in making improvements. The principal research tool applied is the Delphi method, which systematically gathered the knowledge and experience of eighty eight experts in Mexico. The model is validated using a case study and interviews with experts in supply chain management. The resulting contribution is a holistic model of the supply chain integrating multiple perspectives, and providing a systematic procedure for the improvement of a company’s supply chain operations.

Measuring effectiveness in international financial crime prevention: Can we agree on a performance metric?

The attempts at carrying out terrorist attacks have become more prevalent. As a result, an increasing number of countries have become particularly vigilant against the means by which terrorists raise funds to finance their draconian acts against human life and property. Among the many counter-terrorism agencies in operation, governments have set up financial intelligence units (FIUs) within their borders for the purpose of tracking down terrorists’ funds. By investigating reported suspicious transactions, FIUs attempt to weed out financial criminals who use these illegal funds to finance terrorist activity. The prominent role played by FIUs means that their performance is always under the spotlight. By interviewing experts and conducting surveys of those associated with the fight against financial crime, this study investigated perceptions of FIU performance on a comparative basis between American and non-American FIUs. The target group of experts included financial institution personnel, civilian agents, law enforcement personnel, academicians, and consultants. Questions for the interview and surveys were based on the Kaplan and Norton’s Balanced Scorecard (BSC) methodology. One of the objectives of this study was to help determine the suitability of the BSC to this arena. While FIUs in this study have concentrated on performance by measuring outputs such as the number of suspicious transaction reports investigated, this study calls for a focus on outcomes involving all the parties responsible for financial criminal investigations. It is only through such an integrated approach that these various entities will be able to improve performance in solving financial crime. Experts in financial intelligence strongly believed that the quality and timeliness of intelligence was more important than keeping track of the number of suspicious transaction reports. Finally, this study concluded that the BSC could be appropriately applied to the arena of financial crime prevention even though the emphasis is markedly different from that in the private sector. While priority in the private sector is given to financial outcomes, in this arena employee growth and internal processes were perceived as most important in achieving a satisfactory outcome.

Controlled growth of carbon nanotubes for high performance nanoelectronics

Unique electrical and mechanical properties of single-walled carbon nanotubes (SWNTs) have made them one of the most promising candidates for next-generation nanoelectronics. Efficient utilization of the exceptional properties of SWNTs requires controlling their growth direction (e.g., vertical, horizontal) and morphologies (e.g., straight, junction, coiled). ^ In this dissertation, the catalytic effect on the branching of SWNTs, Y-shaped SWNTs (Y-SWNTs), was investigated. The formation of Y-shaped branches was found to be dependent on the composition of the catalysts. Easier carbide formers have a strong tendency to attach to the sidewall of SWNTs and thus enhance the degree of branching. Y-SWNTs based field-effect transistors (FETs) were fabricated and modulated by the metallic branch of the Y-SWNTs, exhibiting ambipolar characteristics at room temperature. A subthreshold swing of 700 mV/decade and an on/off ratio of 105 with a low off-state current of 10-13 A were obtained. The transport phenomena associated with Y- and cross-junction configurations reveals that the conduction mechanism in the SWNT junctions is governed by thermionic emission at T > 100 K and by tunneling at T < 100 K. ^ Furthermore, horizontally aligned SWNTs were synthesized by the controlled modification of external fields and forces. High performance carbon nanotube FETs and logic circuit were demonstrated utilizing the aligned SWNTs. It is found that the hysteresis in CNTFETs can be eliminated by removing absorbed water molecules on the CNT/SiO2 interface by vacuum annealing, hydrophobic surface treatment, and surface passivation. SWNT “serpentines” were synthesized by utilization of the interaction between drag force from gas flow and Van der Waals force with substrates. The curvature of bent SWNTs could be tailored by adjusting the gas flow rate, and changing the gas flow direction with respect to the step-edges on a single-crystal quartz substrate. Resistivity of bent SWNTs was observed to increase with curvature, which can be attributed to local deformations and possible chirality shift at curved part. ^ Our results show the successful synthesis of SWNTs having controllable morphologies and directionality. The capability of tailoring the electrical properties of SWNTs makes it possible to build an all-nanotube device by integrating SWNTs, having different functionalities, into complex circuits. ^

Evaluating the impacts of Bolsa Escola programs on student performance in Brazil

Since the 1980s, governments and organizations have promoted cash transfers in education as a tool for motivating elementary aged children to attend school. Oftentimes, the monthly payments supplemented the income a child would be making in the labor market. In Brazil, where these Bolsa or grant programs were pioneered, there has been much success in removing children from harsh labor conditions and increasing enrollment rates among the poorest families. However, the capacity of Bolsa Escola programs to meet other objectives, such as impacting educational outcomes and reducing incidences of poverty, continues to be examined. As these programs continue to be adopted globally, funding millions of children and families, evidence that demonstrates such success becomes ever more imperative. This study, therefore, examined evidence to determine whether Bolsa Escola programs have a significant impact on the academic performance of beneficiaries in Brazil. ^ Through the course of three data collection phases, multiple data sources were used to demonstrate the academic performance of fourth and eighth grade Brazilian students who were eligible to participate in either an NGO or the federal cash transfer program. MANOVAs were conducted separately for fourth and eighth grade data to determine if significant differences existed between measures of academic performance of Bolsa and non-Bolsa students. In every case and for both grade levels, significant effects were found for participation. ^ The limited qualitative data collected did not support drawing conclusions. Thematic analysis of the limited interview data pointed to possible dependency on Bolsa monthly stipends, and reallocation of responsibilities in the home in cases where children shifted from being breadwinners to students. ^

Improving storage performance through layout optimizations

Disk drives are the bottleneck in the processing of large amounts of data used in almost all common applications. File systems attempt to reduce this by storing data sequentially on the disk drives, thereby reducing the access latencies. Although this strategy is useful when data is retrieved sequentially, the access patterns in real world workloads is not necessarily sequential and this mismatch results in storage I/O performance degradation. This thesis demonstrates that one way to improve the storage performance is to reorganize data on disk drives in the same way in which it is mostly accessed. We identify two classes of accesses: static, where access patterns do not change over the lifetime of the data and dynamic, where access patterns frequently change over short durations of time, and propose, implement and evaluate layout strategies for each of these. Our strategies are implemented in a way that they can be seamlessly integrated or removed from the system as desired. We evaluate our layout strategies for static policies using tree-structured XML data where accesses to the storage device are mostly of two kinds—parent-to-child or child-to-sibling. Our results show that for a specific class of deep-focused queries, the existing file system layout policy performs better by 5–54X. For the non-deep-focused queries, our native layout mechanism shows an improvement of 3–127X. To improve performance of the dynamic access patterns, we implement a self-optimizing storage system that performs rearranges popular block accesses on a dedicated partition based on the observed workload characteristics. Our evaluation shows an improvement of over 80% in the disk busy times over a range of workloads. These results show that applying the knowledge of data access patterns for allocation decisions can substantially improve the I/O performance.