Prediction of university students' academic achievement by linear and logistic models

University students' academic achievement measured by means of academic progress is modeled through linear and logistic regression, employing prior achievement and demographic factors as predictors. The main aim of the present paper is to compare results yielded by both statistical procedures, in order to identify the most suitable approach in terms of goodness of fit and predictive power. Grades awarded in basic scientific courses and demographic variables were entered into the models at the first step. Two hypotheses are proposed: (a) Grades in basic courses as well as demographic factors are directly related to academic progress, and (b) Logistic regression is more appropriate than linear regression due to its higher predictive power. Results partially confirm the first prediction, as grades are positively related to progress. However, not all demographic factors considered proved to be good predictors. With regard to the second hypothesis, logistic regression was shown to be a better approach than linear regression, yielding more stable estimates with regard to the presence of ill-fitting patterns.     

Maternal concepts and expectations regarding a preterm infant

The objective of the present study was: (a) to identify the concerns, verbally expressed, of 50 mothers regarding their preterm infants (PT) and then compare their verbal expression with those of 25 mothers of full-term infants (FT); and (b) to correlate the mothers' verbal expressions with maternal and infant variables. The following instruments were used to compose and characterize the sample: Structure Clinical Interview for DSM III-R Non-Patient (SCID/NP), State-Trait Anxiety Inventory (STAI), Beck Depression Inventory (BDI), and medical charts. Results showed that there was no difference between groups in term of mothers' expectations and conceptualizations; both groups exhibited predominantly positive expectations and concepts. In comparison with FT mothers, PT mothers verbally expressed more feelings and reactions predominantly negative or conflicting in relation to infant birth. Higher levels of maternal anxiety and depression in the PT Group were correlated with more verbal expressions about negative or conflicting emotions. In addition, lower birth weight, higher neonatal risk and longer length of stay in intensive care nursery of the infants were related with more negative or conflicting concepts by the mothers.     

A comparison of the peers method and traditional methodologies, and risk behaviors in studies of the prevalence of drug consumption in a population of female, Chilean students

The present study investigates drug consumption and risk behaviors among female students between 8th and 12th grade in two communities in the city of Santiago, Chile. Based on studies of university populations, we hypothesize that the students' reports of their consumption of licit drugs will tend to be consistent with their actual use of said drugs using two methods to investigate consumption, while their consumption of illicit drugs will be susceptible, and will tend to be under-reported when evaluated through traditional self-report measures. In order to compare the two methods, a cross-sectional study was designed that would compare reported drug consumption, first using the peers method, and then by means of traditional self-report in a group of 350 students. The results show that women's reports of licit drug consumption converge using the two methods, while as earlier suggested, women's illicit drug consumption was found to be under-reported when traditional methodologies were used.     

Comparison of single- and double-stage designs in the prevalence estimation of eating disorders in community samples

The aim of this research was to compare two different case-identification designs: (a) a one-stage anonymous design using the Eating Disorders Examination-Questionnaire (EDE-Q; Fairburn & Beglin, 1994) as diagnostic instrument and (b) a two-stage-non-anonymous design using the Eating Attitudes Test (EAT; Garner & Garfinkel, 1979) and the EDE-Q as screening instruments and the clinical interview Eating Disorders Examination (EDE; Fairbumrn & Cooper, 1993) as diagnostic instrument, in the estimation of eating disorders prevalence in community samples. Both epidemiological designs were compared in: eating disorders prevalence, population at risk, and weekly frequency of associated symptomatology (binge eating episodes, self-vomiting) within a sample of 559 scholars (14 to 18 year-old males and females) studying in the region of Madrid. Eating disorders prevalence estimation using single-stage design was 6.2%, and 3% using the two-stage design; however, these differences were not significant (p = .067). No significant differences between the two procedures were found either in population at risk or in weekly frequency of reported self-vomiting. Reported binge eating episodes were higher in the one-stage design. The use of a two-stage procedure with clinical interview (vs. questionnaire) leads to a better understanding of the items (specially the most ambiguous ones) and thus, to a more accurate prevalence estimation.     

Motivational profiles and flow in physical education lessons

The purpose of this study was to use cluster analysis to identify differences in goal orientation and motivational climate profiles among students in physical education classes as well as differences among the observed clusters on perceived flow experiences. 983 students of 14- to 15-yr.-olds (M = 14.8 yr., SD = 0.91) from a large Spanish metropolitan school district were participants and completed questionnaires assessing goal orientations, motivational climates, and perceived flow. Analysis showed three distinct clusters with 40.3% of the sample with a High Motivation cluster, 27.6% in a Low Motivation cluster, and 32.2% in a Mastery Motivation cluster. These three clusters differed significantly in ratings of perceived flow. Clusters also showed different composition by sex. Implications of these results with regard to instruction in physical education classes are discussed.     

Structure and conventions

Wayne Davis’s Meaning, Expression and Thought argues that linguistic meaning is conventional use to express ideas. An obvious problem with this proposal is that complex expressions that have never been used are nonetheless meaningful. In response to this concern, Davis associates conventions of use not only with linguistic expressions but also with the modes in which such expressions can combine into larger expressions. I argue that such constructive conventions are in conflict with the principle of compositionality (as it is usually understood) and that (at least in the cases Davis considers) they are unnecessary for semantic explanations.

A practical method for analyzing factorial designs with heteroscedastic data

The Type I error rates and powers of three recent tests for analyzing nonorthogonal factorial designs under departures from the assumptions of homogeneity and normality were evaluated using Monte Carlo simulation. Specifically, this work compared the performance of the modified Brown-Forsythe procedure, the generalization of Box's method proposed by Brunner, Dette, and Munk, and the mixed-model procedure adjusted by the Kenward-Roger solution available in the SAS statistical package. With regard to robustness, the three approaches adequately controlled Type I error when the data were generated from symmetric distributions; however, this study's results indicate that, when the data were extracted from asymmetric distributions, the modified Brown-Forsythe approach controlled the Type I error slightly better than the other procedures. With regard to sensitivity, the higher power rates were obtained when the analyses were done with the MIXED procedure of the SAS program. Furthermore, results also identified that, when the data were generated from symmetric distributions, little power was sacrificed by using the generalization of Box's method in place of the modified Brown-Forsythe procedure.     

On the Relationships between Sum Score Based Estimation and Joint Maximum Likelihood Estimation

This paper analyzes the sum score based (SSB) formulation of the Rasch model, where items and sum scores of persons are considered as factors in a logit model. After reviewing the evolution leading to the equality between their maximum likelihood estimates, the SSB model is then discussed from the point of view of pseudo-likelihood and of misspecified models. This is then employed to provide new insights into the origin of the known inconsistency of the difficulty parameter estimates in the Rasch model. The main results consist of exact relationships between the estimated standard errors for both models; and, for the ability parameters, an upper bound for the estimated standard errors of the Rasch model in terms of those for the SSB model, which are more easily available. The authors acknowledge partial financial support from the FONDECYT Project No. 1060722 from the Chilean Government, and the BIL05/03 grant to P. De Boeck, E. Lesaffre and G. Molenberghs (Flanders) for a collaboration with G. del Pino, E. San Martín, F. Quintana and J. Manzi (Chile).