Inferences about Parameters of Trivariate Normal Distribution with Missing Data

Multivariate normal distribution is commonly encountered in any field, a frequent issue is the missing values in practice. The purpose of this research was to estimate the parameters in three-dimensional covariance permutation-symmetric normal distribution with complete data and all possible patterns of incomplete data. In this study, MLE with missing data were derived, and the properties of the MLE as well as the sampling distributions were obtained. A Monte Carlo simulation study was used to evaluate the performance of the considered estimators for both cases when ρ was known and unknown. All results indicated that, compared to estimators in the case of omitting observations with missing data, the estimators derived in this article led to better performance. Furthermore, when ρ was unknown, using the estimate of ρ would lead to the same conclusion.

Local officials' preferences of performance measurements: A study of local police services

The purpose of this study is to identify the determinants of local officials' preferences of performance measures under the assumption that public officials' consensus on performance measures can enhance the accountability in public service delivery. This research consists of two steps: multiple case studies and a survey. The author conducted the case studies in five general-purpose municipalities in Florida, interviewing 25 local officials, attending community meetings, and reviewing relevant local documents. Based on the case studies and the relevant literature, a survey was developed and sent to 445 local officials in 67 general-purpose municipalities in Dade, Broward, and Palm Beach Counties, Florida. The findings of the case studies and the survey suggest that local officials' preferences of performance measures are influenced by their perception of utilities of performance measures and their desire to measure the achievement of organizational goals. The author concludes that a consensus among local officials for outcome-oriented performance measures is easier to achieve if a prospective performance measurement system is designed for reporting and management purposes rather than for budgeting purposes. ^

Adult education directors' perceptions of performance indicators for adult education programs in the state of Florida

Current demands for accountability in education emphasize outcome-based program evaluation and tie program funding to individual student performance. As has been the case for elementary and secondary programs, demands for accountability have increased pressure on adult educators to show evidence of the benefits of their programs in order to justify their financial support. In Florida, recent legislation fundamentally changes the delivery of adult education in the state by establishing a performance-based funding system that is based on outcomes related to the retention, completion, and employment of program participants.^ A performance-based funding system requires an evaluation process that stresses outcome indicators over indicators that focus on program context or process. Although the state has adopted indicators of program quality to evaluate its adult education programs, these indicators focus mostly on program processes rather than student outcomes. In addition, the indicators are not specifically tied to workforce development outcomes, a priority to federal and local funding agents.^ Improving the accountability of adult education programs and defining the role of these programs in Florida's Workforce Development System has become a priority to policy makers across the state. Another priority has been to involve adult education practitioners in every step of this process.^ This study was conducted in order to determine what performance indicators, as judged by the directors and supervisors of adult education programs in the state of Florida, are important and feasible in measuring the quality and effectiveness of these programs. The results of the study indicated that, both statewide and by region, the respondents consistently gave the highest ratings on both importance and feasibility to the indicators of Program Context, which reflect the needs, composition, and structure of the programs, and to the indicators of Educational Gain, which reflect learner progress in the attainment of basic skills and competencies. In turn, the respondents gave the lowest ratings on both importance and feasibility to the indicators in the areas of Return on State's Investment, Efficiency, Retention, and Workforce Training. In general, the indicators that received high ratings for importance also received high ratings for feasibility. ^

When is personality a predictor of performance? The moderating role of autonomy

The study described herein examined personality as a predictor of task and contextual performance. The Big Five personality dimensions (i.e., Neuroticism, Extraversion, Agreeableness, Openness to Experience, and Conscientiousness) were studied in relation to both task and contextual performance within an organization in the service industry. The situational factor, autonomy, was examined as a potential moderator for the hypothesized personality-contextual performance relationship. Hierarchical regression analyses indicated that Conscientiousness was a valid predictor of task performance, Neuroticism was a valid predictor of contextual performance, and Extraversion was a valid predictor of delinquent performance. However, results did not yield support for the moderating role of autonomy on the personality-contextual performance relationship. Nevertheless, job satisfaction did moderate the Openness to Experience-delinquent performance relationship. Practical implications of these results and suggestions for future research are discussed. ^

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.

The relationship of thymulin activity, immune parameters of HIV disease progression and substance use in a cohort of HIV seropositive alcohol and drug users

Zinc is essential for the activity of thymulin, a thymic hormone involved in T-lymphocyte differentiation and activation. Zinc deficiency is widespread in populations with HIV infection, and HIV+ drug users are particularly susceptible to zinc deficiency and immune suppression. This dissertation explored the relationship of zinc-bound active thymulin to plasma zinc, CD4+ and CD8+ cell count, the CD4+/CD8+ ratio, and drug use in HIV-infected drug users. Zinc-bound active thymulin was assessed in plasma of HIV+ drug users who were participating in a 30 month zinc supplementation trial. Plasma from 80 participants at the 12 month visit, and 40 of these same participants, randomly selected, at the baseline visit were assessed for zinc-bound active thymulin levels using a modification of the rosette inhibition assay. Thymulin activity was directly associated with CD4+ cell count (β = 0.127, p = 0.002) and inversely associated with cocaine use (β = −0.908, p = 0.026; R2 = 0.188, p = 0.019) independent of HIV viral load, age, gender and antiretroviral use. An increase in thymulin activity was 1.4 times more likely when CD4+ cell count increased (OR = 1.402, 95%CI: 1.006–1.956), independent of change in viral load, antiretroviral use, and age. Participants who used cocaine consistently, were 7.6 times less likely to have an increase in thymulin activity (OR = 0.133, 95%CI: 0.017–1.061). There was a direct correlation between change in plasma zinc and change in zinc-bound active thymulin (r = 0.243, p = 0.13). Analysis of CD4+ cell count decline in 222 participants in the zinc supplementation trial across the 30 months showed that both crack cocaine use and heavy alcohol use accelerated CD4+ cell count decline. Thymulin activity is directly associated with HIV disease progression, measured by CD4+ cell count, and is depressed with cocaine use independent of antiretroviral use and HIV viral load. Cocaine and heavy alcohol accelerate CD4+ cell count decline. The effect of cocaine on thymic output requires further evaluation as a mechanism for the association of cocaine use with faster HIV disease progression.

The Use of Performance Appraisal Systems in Restaurants

Do restaurant managers commonly use performance appraisals and, if so, how frequently anf for what purposes? The authors address these questions and review the restaurant industry in general.

The effects of hydroperiod on the life-history parameters of Lucania goodei (fundulidae) in the Florida Everglades

In aquatic ecosystems, hydrological fluctuation may generate a gradient of lifehistory responses associated with marsh drying. This study was conducted in the Florida Everglades to document spatial and temporal variability in growth and survivorship of the bluefin killifish (Lucania goodei) from six populations along a hydroperiod gradient. The otolith-microstructure analysis of field-collected fish was used to estimate growth rate and those data were combined with field-density estimates for survivorship analysis. Otolith analysis revealed that L. goodei is extremely short-lived with no variation in growth rates and very little spatial or temporal variation in survivorship. These results suggest that bluefin killifish populations experience similar life histories across a diversity of hydroperiods either through well-mixed populations homogenizing these vital rates, or more likely, that a multitude of factors force L. goodei to respond to these "stressors" in a similar fashion across hydroperiod gradients.

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.