Guillermo Vallejo
Biographic Data
| ID | 5706670 |
|---|---|
| NAME | Guillermo Vallejo |
| GIVEN NAMES | Guillermo |
| FAMILY NAME | Vallejo |
| SIGNATURE | VALLEJO G |
| AFFILIATIONS | Universidad de Oviedo |
| ORCID | 0000-0002-8010-6854 |
| VERIFIED | Yes |
| TOTAL WORKS | 16 |
| TOTAL CITATIONS | 2 |
| AUTHOR COUNT | 16 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 2001 |
| LATEST PUBLICATION YEAR | 2025 |
| H-INDEX | 1 |
Impulsivity traits moderate the longitudinal association between mental health and hazardous cannabis use in emerging adults
Elementary school students’ attitudes towards cerebral palsy
The present study developed a brief school-based intervention focused on raising awareness about Cerebral Palsy. To assess the effectiveness of the intervention, 91 classes from the fourth and fifth grades were randomly assigned to one of three conditions: Control, Focused on the Domain (Cerebral Palsy), and Non-Focused on the Domain (promotion of inclusion in general). Groups were assessed in three waves: pre-test, post-test, and follow-up. Data…
A brief school-based intervention on Gypsy culture
Gypsy children low school engagement, high rates of school dropout, and pervasive school failure are relevant societal challenges that may be explained by Gypsy people cultural mores, but also by the discriminatory behaviors of school peers. The latter may be a consequence of insufficient accurate knowledge of Gypsy culture. The present study developed a brief school-based intervention targeting the whole class with a focus on raising awareness o…
Promoting School Engagement in Children with Cerebral Palsy
This study assessed the efficacy of an educational program focused on the promotion of school engagement in children with Cerebral Palsy. A 9 weeks, narrative-based intervention program, with a pre-post neuropsychological and self-report evaluation, was developed with a dual focus: a self-regulation theoretical model and executive function stimulation. Fifteen children with Cerebral Palsy participated in the study. Results showed a significant ma…
Influence of initial mathematical competencies on the effectiveness of a classroom‐based intervention
BACKGROUND: Students commonly struggle with mathematics and mathematical problem-solving. Therefore, it is necessary to design and implement interventions aimed at improving these essential components of learning. Furthermore, the outcomes of these interventions can vary significantly and appear to be a function of a student's initial competencies in mathematics. AIM: This study attempts to analyse the influence of initial levels of mathematics c…
Eudaimonic Well-Being and Coping with Stress in University Students
The importance of personal psychological resources in preventing academic stress has enjoyed little attention to date, despite the high rates of stress that exist among university students. This article analyzes the effect of eudaimonic well-being on the use of adaptive strategies for coping with academic stress. Moreover, it analyzes the role of self-efficacy as a mediator and moderator of this relationship. In the mediation model, gender is inc…
Promoting Gypsy children's behavioural engagement and school success
Low schooling, high non‐attendance and school dropout rates are critical phenomena within disadvantaged groups, especially among the Gypsy community. For example, in the UK , 10%–25% of Gypsy children do not attend school regularly and have significantly higher levels of overall absence from school (percentage of half‐day sessions missed) than pupils from other ethnic groups. In Portugal, available data on Gypsy children is sparse, yet data from …
Effects of Modeling the Heterogeneity on Inferences Drawn from Multilevel Designs
This article uses Monte Carlo techniques to examine the effect of heterogeneity of variance in multilevel analyses in terms of relative bias, coverage probability, and root mean square error (RMSE). For all simulated data sets, the parameters were estimated using the restricted maximum-likelihood (REML) method both assuming homogeneity and incorporating heterogeneity into multilevel models. We find that (a) the estimates for the fixed parameters …
Comparison of Modern Methods for Analyzing Repeated Measures Data With Missing Values
Missing data are a pervasive problem in many psychological applications in the real world. In this article we study the impact of dropout on the operational characteristics of several approaches that can be easily implemented with commercially available software. These approaches include the covariance pattern model based on an unstructured covariance matrix (CPM-U) and the true covariance matrix (CPM-T), multiple imputation-based generalized est…
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 ava…
Comparative Robustness of Recent Methods for Analyzing Multivariate Repeated Measures Designs
This study evaluated the robustness of two recent methods for analyzing multivariate repeated measures when the assumptions of covariance homogeneity and multivariate normality are violated. Specifically, the authors' work compares the performance of the modified Brown—Forsythe (MBF) procedure and the mixed-model procedure adjusted by the Kenward—Roger solution available in SAS PROC MIXED. The authors found that, overall, the MBF procedure appear…
A Comparison of the Bootstrap-F, Improved General Approximation, and Brown-Forsythe Multivariate Approaches in a Mixed Repeated Measures Design
The authors compare the operating characteristics of the bootstrap- F approach, a direct extension of the work of Berkovits, Hancock, and Nevitt, with Huynh’s improved general approximation (IGA) and the Brown-Forsythe (BF) multivariate approach in a mixed repeated measures design when normality and multisample sphericity assumptions do not hold. The results of the simulation show that the three approaches adequately control Type I error when dat…
Modified Brown–Forsythe Procedure for Testing Interaction Effects in Split-Plot Designs
The standard univariate and multivariate methods are conventionally used to analyze continuous data from groups by trials repeated measures designs, in spite of being extremely sensitive to departures from the multisample sphericity assumption when group sizes are unequal. However, in the last 10 years several authors have offered alternative solutions to these tests that do not rest on this assumption. In an attempt to improve the precision of t…
Comparison of Two Procedures for Analyzing Small Sets of Repeated Measures Data
This article compares two methods for analyzing small sets of repeated measures data under normal and non-normal heteroscedastic conditions: a mixed model approach with the Kenward-Roger correction and a multivariate extension of the modified Brown-Forsythe (BF) test. These procedures differ in their assumptions about the covariance structure of the data and in the method of estimation of the parameters defining the mean structure. Simulation res…
Application of a Mixed Model Approach for Assessment of Interventions and Evaluation of Programs
Many social programs and programs for prevention of drug use are designed to affect a wide variety of targets, including individuals, families and neighborhoods, and organizations such as schools, companies, or hospitals. The nature of the intervention and the design of the particular study determine the choice of the appropriate unit of analysis in assessments of outcome. When the units of assignment and units of observation differ from one anot…
Effects of Covariance Heterogeneity on Three Procedures for Analyzing Multivariate Repeated Measures Designs
Empirical Type I error and power rates were estimated for (a) the doubly multivariate model, (b) the Welch-James multivariate solution developed by Keselman, Carriere and Lix (1993) using Johansen's results (1980), and for (c) the multivariate version of the modified Brown-Forsythe (1974) procedure. The performance of these procedures was investigated by testing within- blocks sources of variation in a multivariate split-plot design containing un…
Promoting Gypsy children's behavioural engagement and school success
Low schooling, high non‐attendance and school dropout rates are critical phenomena within disadvantaged groups, especially among the Gypsy community. For example, in the UK , 10%–25% of Gypsy children do not attend school regularly and have significantly higher levels of overall absence from school (percentage of half‐day sessions missed) than pupils from other ethnic groups. In Portugal, available data on Gypsy children is sparse, yet data from …
Effects of Covariance Heterogeneity on Three Procedures for Analyzing Multivariate Repeated Measures Designs
Empirical Type I error and power rates were estimated for (a) the doubly multivariate model, (b) the Welch-James multivariate solution developed by Keselman, Carriere and Lix (1993) using Johansen's results (1980), and for (c) the multivariate version of the modified Brown-Forsythe (1974) procedure. The performance of these procedures was investigated by testing within- blocks sources of variation in a multivariate split-plot design containing un…
Application of a Mixed Model Approach for Assessment of Interventions and Evaluation of Programs
Many social programs and programs for prevention of drug use are designed to affect a wide variety of targets, including individuals, families and neighborhoods, and organizations such as schools, companies, or hospitals. The nature of the intervention and the design of the particular study determine the choice of the appropriate unit of analysis in assessments of outcome. When the units of assignment and units of observation differ from one anot…
Comparison of Two Procedures for Analyzing Small Sets of Repeated Measures Data
This article compares two methods for analyzing small sets of repeated measures data under normal and non-normal heteroscedastic conditions: a mixed model approach with the Kenward-Roger correction and a multivariate extension of the modified Brown-Forsythe (BF) test. These procedures differ in their assumptions about the covariance structure of the data and in the method of estimation of the parameters defining the mean structure. Simulation res…
A Comparison of the Bootstrap-F, Improved General Approximation, and Brown-Forsythe Multivariate Approaches in a Mixed Repeated Measures Design
The authors compare the operating characteristics of the bootstrap- F approach, a direct extension of the work of Berkovits, Hancock, and Nevitt, with Huynh’s improved general approximation (IGA) and the Brown-Forsythe (BF) multivariate approach in a mixed repeated measures design when normality and multisample sphericity assumptions do not hold. The results of the simulation show that the three approaches adequately control Type I error when dat…
Modified Brown–Forsythe Procedure for Testing Interaction Effects in Split-Plot Designs
The standard univariate and multivariate methods are conventionally used to analyze continuous data from groups by trials repeated measures designs, in spite of being extremely sensitive to departures from the multisample sphericity assumption when group sizes are unequal. However, in the last 10 years several authors have offered alternative solutions to these tests that do not rest on this assumption. In an attempt to improve the precision of t…
Comparative Robustness of Recent Methods for Analyzing Multivariate Repeated Measures Designs
This study evaluated the robustness of two recent methods for analyzing multivariate repeated measures when the assumptions of covariance homogeneity and multivariate normality are violated. Specifically, the authors' work compares the performance of the modified Brown—Forsythe (MBF) procedure and the mixed-model procedure adjusted by the Kenward—Roger solution available in SAS PROC MIXED. The authors found that, overall, the MBF procedure appear…
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 ava…
Comparison of Modern Methods for Analyzing Repeated Measures Data With Missing Values
Missing data are a pervasive problem in many psychological applications in the real world. In this article we study the impact of dropout on the operational characteristics of several approaches that can be easily implemented with commercially available software. These approaches include the covariance pattern model based on an unstructured covariance matrix (CPM-U) and the true covariance matrix (CPM-T), multiple imputation-based generalized est…
Effects of Modeling the Heterogeneity on Inferences Drawn from Multilevel Designs
This article uses Monte Carlo techniques to examine the effect of heterogeneity of variance in multilevel analyses in terms of relative bias, coverage probability, and root mean square error (RMSE). For all simulated data sets, the parameters were estimated using the restricted maximum-likelihood (REML) method both assuming homogeneity and incorporating heterogeneity into multilevel models. We find that (a) the estimates for the fixed parameters …
Promoting Gypsy children's behavioural engagement and school success
Low schooling, high non‐attendance and school dropout rates are critical phenomena within disadvantaged groups, especially among the Gypsy community. For example, in the UK , 10%–25% of Gypsy children do not attend school regularly and have significantly higher levels of overall absence from school (percentage of half‐day sessions missed) than pupils from other ethnic groups. In Portugal, available data on Gypsy children is sparse, yet data from …
Eudaimonic Well-Being and Coping with Stress in University Students
The importance of personal psychological resources in preventing academic stress has enjoyed little attention to date, despite the high rates of stress that exist among university students. This article analyzes the effect of eudaimonic well-being on the use of adaptive strategies for coping with academic stress. Moreover, it analyzes the role of self-efficacy as a mediator and moderator of this relationship. In the mediation model, gender is inc…
Promoting School Engagement in Children with Cerebral Palsy
This study assessed the efficacy of an educational program focused on the promotion of school engagement in children with Cerebral Palsy. A 9 weeks, narrative-based intervention program, with a pre-post neuropsychological and self-report evaluation, was developed with a dual focus: a self-regulation theoretical model and executive function stimulation. Fifteen children with Cerebral Palsy participated in the study. Results showed a significant ma…
Influence of initial mathematical competencies on the effectiveness of a classroom‐based intervention
BACKGROUND: Students commonly struggle with mathematics and mathematical problem-solving. Therefore, it is necessary to design and implement interventions aimed at improving these essential components of learning. Furthermore, the outcomes of these interventions can vary significantly and appear to be a function of a student's initial competencies in mathematics. AIM: This study attempts to analyse the influence of initial levels of mathematics c…
A brief school-based intervention on Gypsy culture
Gypsy children low school engagement, high rates of school dropout, and pervasive school failure are relevant societal challenges that may be explained by Gypsy people cultural mores, but also by the discriminatory behaviors of school peers. The latter may be a consequence of insufficient accurate knowledge of Gypsy culture. The present study developed a brief school-based intervention targeting the whole class with a focus on raising awareness o…
Elementary school students’ attitudes towards cerebral palsy
The present study developed a brief school-based intervention focused on raising awareness about Cerebral Palsy. To assess the effectiveness of the intervention, 91 classes from the fourth and fifth grades were randomly assigned to one of three conditions: Control, Focused on the Domain (Cerebral Palsy), and Non-Focused on the Domain (promotion of inclusion in general). Groups were assessed in three waves: pre-test, post-test, and follow-up. Data…
Impulsivity traits moderate the longitudinal association between mental health and hazardous cannabis use in emerging adults
Mathematics (9 works) · Statistics (9 works) · Psychology (8 works) · Statistical Methods and Bayesian Inference (6 works) · Type I and type II errors (6 works) · Advanced Statistical Methods and Models (5 works) · Computer Science (5 works) · Developmental psychology (5 works) · Econometrics (5 works) · Medicine (5 works)