Search results for "Variable"
showing 10 items of 1674 documents
Returns to Schooling in Spain: How Reliable are Instrumental Variable Estimates?
2002
This paper studies the ordinary least–squares (OLS) and instrumental variable (IV) estimates of the returns to schooling for male workers in Spain. OLS estimates are often biased due to the endogeneity of schooling, measurement errors or omitted variables. Proper IV estimates correct this bias. The reliability of family background, natural experiments (based on changes in the education system and season of birth) and the availability of a college in the province is checked using Spanish data. The results suggest that background and college availability are valid instruments and that the IV estimates of the returns to schooling are higher than OLS estimates. These results are in line with th…
Returns to Schooling in Spain. How Reliable Are IV Estimates?
2001
This paper studies the Ordinary Least-Squared (OLS) and Instrumental Variables (IV) estimates of the returns to schooling for male workers in Spain. OLS estimates are often biased due to the endogeneity of schooling, measurement errors or omitted variables. Proper IV estimates correct this bias. The reliability of family background, natural experiments (based on changes in the education system and season of birth) and the availability of a college in the province is checked using Spanish data. The results suggest that background and college availability are valid instruments and that the IV estimates of the returns to schooling are higher than OLS estimates. These results are in line with t…
Inferring heterozygosity from ancient and low coverage genomes
2016
Abstract While genetic diversity can be quantified accurately from high coverage sequencing data, it is often desirable to obtain such estimates from data with low coverage, either to save costs or because of low DNA quality, as is observed for ancient samples. Here, we introduce a method to accurately infer heterozygosity probabilistically from sequences with average coverage <1× of a single individual. The method relaxes the infinite sites assumption of previous methods, does not require a reference sequence, except for the initial alignment of the sequencing data, and takes into account both variable sequencing errors and potential postmortem damage. It is thus also applicable to …
CSF neurofilament proteins as diagnostic and prognostic biomarkers for amyotrophic lateral sclerosis
2017
Elevated cerebrospinal fluid (CSF), Neurofilament Light (NF-L) and phosphorylated Heavy (pNF-H) chain levels have been found in Amyotrophic Lateral Sclerosis (ALS), with studies reporting a correlation of both neurofilaments (NFs) with the disease progression. Here, we measured NF-L and pNF-H concentrations in the CSF of ALS patients from a single tertiary Center and investigated their relationship with disease-related variables. A total of 190 ALS patients (Bulbar, 29.9%; Spinal, 70.1%; M/F = 1.53) and 130 controls with mixed neurological diseases were recruited. Demographic and clinical variables were recorded, and Delta FS was used to rate the disease progression. Controls were divided i…
Sample size planning of two-arm superiority and noninferiority survival studies with discrete follow-up
2016
In clinical trials using lifetime as primary outcome variable, it is more the rule than the exception that even for patients who are failing in the course of the study, survival time does not become known exactly since follow-up takes place according to a restricted schedule with fixed, possibly long intervals between successive visits. In practice, the discreteness of the data obtained under such circumstances is plainly ignored both in data analysis and in sample size planning of survival time studies. As a framework for analyzing the impact of making no difference between continuous and discrete recording of failure times, we use a scenario in which the partially observed times are assig…
Do Adolescents Who Meet Physical Activity Recommendations on Weekdays Also Meet Them on Weekends? A Cross-Sectional Study in Colombia.
2021
The purpose of this study was to examine whether Colombian adolescents fulfill physical activity (PA) recommendations by type of day depending on several variables. A cross-sectional study was carried out on a sample of 2624 adolescents from Neiva (Colombia) using the Seven Day PA Recall and the Family Affluence Scale II self-reported questionnaires. Statistical analyses were performed to find any differences by gender, socioeconomic status, PA recommendations accomplishment, participation in organized and non-organized PA, parents&rsquo
Resilience and coping as predictors of general well-being in the elderly: A structural equation modeling approach
2012
The aims of this article are: (a) to test for the validity of the three constructs involved in the structural model; (b) to test for the effects of both coping strategies and resilient coping on well-being in a sample of elderly, by means of a structural model with latent variables; (c) to empirically study whether a brief scale of resilient coping could predict well-being over and above that predicted by the coping resources.The research is a survey design. The sample consisted of 225 non-institutionalized elderly people living in the city of Valencia (Spain). The three constructs measured were: well-being, resilient coping, and coping strategies.The analyses consist of a series of alterna…
Domain-general neural correlates of dependency formation: Using complex tones to simulate language
2015
There is an ongoing debate whether the P600 event-related potential component following syntactic anomalies reflects syntactic processes per se, or if it is an instance of the P300, a domain-general ERP component associated with attention and cognitive reorientation. A direct comparison of both components is challenging because of the huge discrepancy in experimental designs and stimulus choice between language and ‘classic’ P300 experiments. In the present study, we develop a new approach to mimic the interplay of sequential position as well as categorical and relational information in natural language syntax (word category and agreement) in a non-linguistic target detection paradigm using…
Prognostic factors and predictors of outcome in children with autism spectrum disorder: the role of the paediatrician.
2021
Abstract Background Autism spectrum disorder is a complex condition with wide variation in type and severity that involves persistent challenges in social interaction, speech and nonverbal communication, restricted/repetitive behaviours and adaptive behaviours. In recent years, research has deepened the study of the predictive factors of optimal outcome, intended as indicators of positive trajectory in children with a previous diagnosis of autism who, after a therapeutic path, show a significant reduction in the “core” symptoms of autism and a positive evolution in social, adaptive, affective, and relational skills. Methods The study included 40 children aged 21 to 66 months, enrolled betwe…
Serum metabolome analysis by 1H-NMR reveals differences between chronic lymphocytic leukaemia molecular subgroups.
2010
Chronic lymphocytic leukaemia (CLL) is a heterogeneous disease exhibiting variable clinical course and survival rates. Mutational status of the immunoglobulin heavy chain variable regions (IGHVs) of CLL cells offers useful prognostic information for high-risk patients, but time and economical costs originally prevented it from being routinely used in a clinical setting. Instead, alternative markers of IGHV status, such as zeta-associated protein (ZAP70) or messenger RNA levels are often used. We report a (1)H-NMR-based metabolomics approach to examine serum metabolic profiles of early stage, untreated CLL patients (Binet stage A) classified on the basis of IGHV mutational status or ZAP70. M…