Many methods have been developed to determine the "appropriate" subset of independent variables in a multiple variable problem. Some of the methods are application specific while others have a wide range of uses. This study compares two such methods, Regression Trees and Stepwise Regression. A simulation using a known distribution is used for the comparison. In 699 out of 742 cases the Regression Tree method gave better predictors than the Stepwise Regression procedure.

Identifying non-tracking individuals in a population of longitudinal data has many applications as well as complications. The analysis of longitudinal data is a special study in itself. There are several accepted methods, of those we chose a two-stage random effects model coupled with the Estimation Maximization Algorithm (E-M Algorithm) . Our project consisted of first estimating population parameters using the previously mentioned methods. The Mahalanobis distance was then used to sequentially identify and eliminate non-trackers from the population. Computer simulations were run in order to measure the algorithm's effectiveness. Our results show that the average specificity for the repetitions for each simulation remained at the 99% level. The sensitivity was best when only a single non-tracker was present with a very different parameter a. The sensitivity of the program decreased when more than one tracker was present, indicating our method of identifying a non-tracker is not effective when the estimates of the population parameters are contaminated.

Isolated populations that inhabit various geographic and climatic ranges tend to diverge in their life history tactics. When development time is constrained by unfavorable seasons, often an organism must trade-off the investment of resource allocation between somatic and reproductive growth. The variation in reproductive tactics and juvenile hormone titers were studied among three populations of Romalea microptera from Athens, GA, Jacksonville, FL, and Miami, FL, all of which exist on a latitudinal cline. The Athens population was significantly younger at oviposition and gained significantly less body mass than both the Jacksonville and Miami populations, which did not differ from each other. Clutch mass did not differ across populations. With respect to both body size and oviposition age, Athens invested significantly more (measured by clutch size) to their first clutch than either Jacksonville or Miami, which did not differ from each other. Juvenile hormone and lipid profiles did not differ among populations. In response to the markedly reduced season length, results suggest that Athens grasshoppers respond with reproductive tactics that support terminal investment by investing more energy in less time to reproduction, at the expense of future reproduction.

Research indicates that classroom behaviors in students may be good predictors of academic success. The present study investigated the relationship between classroom peers, positive and negative classroom behaviors, early literacy and mathematics ability, and classroom model in 214 predominately low-income preschool children in 21 classes across a six-county area. It was hypothesized that peer classroom behavior would be a significant predictor of individual child ability and that peers would have differential influence across classroom models. Results indicated that peer classroom behavior was not a significant predictor of individual child ability. Individual child classroom behaviors, specifically positive behaviors, emerged as a significant predictor of child ability. Peer ability and peer positive classroom behaviors emerged as significant predictors of individual child ability in classrooms that were structured with an academically directed model, but not in classrooms that were more structured with a combination of academic and child-centered models.

A method is described for finding the least squares solution of the overdetermined linear system that arises in the photogrammetric problem of bundle adjustment of aerial photographs. Because of the sparse, blocked structure of the coefficient matrix of the linear system, the proposed method is based on sparse QR factorization using Givens rotations. A reordering of the rows and columns of the matrix greatly reduces the fill-in during the factorization. Rules which predict the fill-in for this ordering are proven based upon the block structure of the matrix. These rules eliminate the need for the usual symbolic factorization in most cases. A subroutine library that implements the proposed method is listed. Timings and populations of a range of test problems are given.

Because a child's first day of school can be anxiety provoking, familiar soothing inanimate objects, such as blankets, might help to minimize discomfort related to this novel situation. The current study examined the anxiety level of twenty-six one- to four-year-old children and their mothers at three times 1) before the first day of school, 2) during separation from their mother on the first day of school, and 3) after home from their first day of school. Maternal report was used to assess child and mother anxiety levels (Likert scale 0- 10) and child level of attachment to a familiar inanimate object. No differences in anxiety levels were found among attached children who brought their attachment object with them on their first day of school, attached children without their objects, and unattached children with or without a familiar object. Children's anxiety did differ among the assessment times, verifying that separation from their mothers on first day of school is a low arousal situation. Mother's anxiety was not positively related to children's anxiety. Future studies might further explore an observed trend of children attached to inanimate objects displaying less anxiety than their unattached counterparts across school-related transitions.

Non-pathological sleep parameters in relation to cognition among individuals who do not qualify as having sleep disorders or who are not subjected to extended periods of total sleep deprivation have not been adequately investigated in previous studies. The current study investigates the influence of circadian typology (morning-type vs. evening-type individuals), time of session (AM vs. PM), habitual sleep practices (sleep hygiene), sleep quality, life stress, and the presence of an acute stressor on sustained attention, memory, and mental rotation performance. Several main effects emerged for individual variables above; however, the data failed to reveal significant interactions among these variables. The evidence in this study of non-pathological sleep parameters affecting cognitive performance presents a need for further investigation.

The Hispanic population in the United States already constitutes the fastest growing minority group in the United States and by the year 2050 this group will constitute 24% of the total population and one fourth of the national workforce. Because this is a very young population whose median age is 27.2 years old, the education of this group is pivotal to the future of this nation. The purpose of this study was to examine the perceived importance of personal and external factors found in the literature as significant in Hispanic college success for a sample of 137 Hispanic college seniors from four public higher education institutions in Florida. This mixed method study used an instrument containing 13 demographic variables, 61 quantitative items, and 5 qualitative questions. The information gathered from the demographic items revealed a relevant data characterizing the participants as first, second, and third generation immigrants or Hispanic Americans with a diverse Hispanic background. They also belonged to middle and upper income households with at least one college educated parent. The results from the descriptive analysis of the quantitative data from the survey indicated the students in the study had a strong desire to succeed, perceived a strong parental support and a supportive campus environment, and had a strong academic preparation to attend college. All these factors were corroborated by the qualitative results. The recommendations for future studies and practices should include a greater understanding of the important role a supportive family and institution play in the academic success of Hispanic students. More research is recommended on the family-student relationship and its effect on students. Reaching out to Hispanic parents and families and ensuring their participation in campus events, as well as increasing institutional support with the outreach and hiring of Hispanic faculty are two specific recommendations worthy of consideration in the effort to ensure greater success for Hispanic students.

The purpose of this concurrent mixed methods study was to explore how well Florida's 2+2 articulation agreement and transfer student services meet the needs of students. Phase I employed quantitative methodology to compare the academic success and persistence to graduation of a single cohort (n = 2,612) of Florida public community college Associate in Arts graduates (n = 1,738) and native (n = 874) juniors (60-to-70 credit hours) who entered the same universities as FTIC. Discriminant analysis results yielded statistically significant differences in the academic success and persistence of community college transfer and native student graduates and dropouts. On average, native students graduated with twice as many lower level credit hours and cumulative credit hours than community college transfers. Discriminant analysis results did not yield appreciable differences in the final grade point averages of student graduates, indicating that community college transfer students performed just as well academically as native students. However, the results of the chi -square tests of independence indicated that a greater percentage of native students graduated and a greater percentage of community college transfer students dropped out of academic degree programs. These findings support the conclusion that community college students are as academically capable as native students but may benefit from services that promote student engagement. The qualitative component provided a context for enhancing the interpretation of quantitative findings and for addressing the structure of articulation services, availability of transfer student services, compliance with the statewide articulation agreement, and advocacy of transfer students on each campus. Interviews with 15 current and previous administrators led to the identification of three significant issues related to the rapidly evolving universities and their primary feeder community colleges.

The purpose of this study was to investigate the effect that heuristics instruction for certain strategies and skills used in the solution of non-routine mathematical problems would have on problem solving behavior. It was conjectured that subjects given compressed but explicit instruction in problem solving strategies would exhibit higher achievement than subjects who did not receive such explicit instruction. Subjects were elementary education student volunteers from the University of North Florida. They were randomly assigned to experimental and control groups for instruction. A pretest and a posttest were administered to collect the data to evaluate this experimental design. The null hypothesis that there would be no difference in the mean gain scores between the experimental and control groups could not be rejected at the .05 level of significance. The results of this study indicate that successful generalization of complex concepts should not be expected following such a short instructional period.