Likelihood inferences with interval-censored data

En l’anàlisi de la supervivència el problema de les dades censurades en un interval es tracta, usualment,via l’estimació per màxima versemblança. Amb l’objectiu d’utilitzar una expressió simplificada de la funció de versemblança, els mètodes estàndards suposen que les condicions que produeixen la censura no afecten el temps de fallada. En aquest article formalitzem les condicions que asseguren la validesa d’aquesta versemblança simplificada. Així, precisem diferents condicions de censura no informativa i definim una condició de suma constant anàloga a la derivada en el context de censura per la dreta. També demostrem que les inferències obtingudes amb la versemblançaa simplificada són correctes quan aquestes condicions són certes. Finalment, tractem la identificabilitat de la funció distribució del temps de fallada a partir de la informació observada i estudiem la possibilitat de contrastar el compliment de la condició de suma constant.

Citacions i referències de fonts bibliogràfiques i no bibliogràfiques: una proposta per a la revista Item.

Proposta per elaborar referències i citacions de tot tipus de fonts bibliogràfiques i no bibliogràfiques, publicades i inèdites i les seves parts. Com a introducció, els autors justifiquen les raons de la proposta i expliquen els models en què es basa. Una vegada aprovades, aquestes directrius aniran adreçades principalment als autors i correctors de la revista Item; tanmateix, també s'espera que siguin emprades per redactar referències i citacions en treballs de biblioteconomia i documentació.

Translation and validation of the Ten-Item-Personality Inventory into spanish and catalan

In response to an increasing need for ever-shorter personality instruments, Gosling, Rentfrow, and Swann (2003) developed the Ten-Item-Personality Inventory (TIPI), which measures the dimensions of the Five Factor Model (FFM) using 10 items (two for each dimension) and can be administered in about one minute. In two studies and using a multi-judge (self and observer) and multi-instrument design, we develop Spanish (Castilian) and Catalan versions of the TIPI and evaluate them in terms of internal consistency, test-retest reliability, convergent, discriminant, and content validity, as well as self-observer correlations. Test-retest correlations were strong, and convergence with the NEO-PI-R factors was significant. There were also strong correlations between observer ratings and the participants’ self-ratings. Despite some inconsistencies with respect to the Agreeableness scale, the Catalan translation and both translations into Spanish of the original TIPI demonstrated sufficient psychometric properties to warrant use as a Five Factor personality measure when the use of longer instruments is not convenient or possible. Furthermore, as the first translation of a brief standard Big Five Instrument into Catalan, this work should facilitate future research on personality in the Catalan-speaking population.

A 14-item Mediterranean diet assessment tool and obesity indexes among high-risk subjects: the PREDIMED trial

Objective: Independently of total caloric intake, a better quality of the diet (for example, conformity to the Mediterranean diet) is associated with lower obesity risk. It is unclear whether a brief dietary assessment tool, instead of full-length comprehensive methods, can also capture this association. In addition to reduced costs, a brief tool has the interesting advantage of allowing immediate feedback to participants in interventional studies. Another relevant question is which individual items of such a brief tool are responsible for this association. We examined these associations using a 14-item tool of adherence to the Mediterranean diet as exposure and body mass index, waist circumference and waist-to-height ratio (WHtR) as outcomes. Design: Cross-sectional assessment of all participants in the"PREvención con DIeta MEDiterránea" (PREDIMED) trial. Subjects: 7,447 participants (55-80 years, 57% women) free of cardiovascular disease, but with either type 2 diabetes or $3 cardiovascular risk factors. Trained dietitians used both a validated 14-item questionnaire and a full-length validated 137-item food frequency questionnaire to assess dietary habits. Trained nurses measured weight, height and waist circumference. Results: Strong inverse linear associations between the 14-item tool and all adiposity indexes were found. For a two-point increment in the 14-item score, the multivariable-adjusted differences in WHtR were 20.0066 (95% confidence interval,- 0.0088 to 20.0049) for women and-0.0059 (-0.0079 to-0.0038) for men. The multivariable-adjusted odds ratio for a WHtR.0.6 in participants scoring $10 points versus #7 points was 0.68 (0.57 to 0.80) for women and 0.66 (0.54 to 0.80) for men. High consumption of nuts and low consumption of sweetened/carbonated beverages presented the strongest inverse associations with abdominal obesity. Conclusions: A brief 14-item tool was able to capture a strong monotonic inverse association between adherence to a good quality dietary pattern (Mediterranean diet) and obesity indexes in a population of adults at high cardiovascular risk.

The factorial structure of the 41-item version of the Screen for Child Anxiety Related Emotional Disorders (SCARED) in a Spanish population of 8 to 12 years-old

On this instrumental study we intend to analyse the factorial structure of the Screen for Child Anxiety Related Emotional Disorders (SCARED) in a Spanish sample using exploratory and confirmatory factorial analysis. As a second objective we intend to develop a short form of it for rapid screening and, finally, to analyze the reliabilities of both questionnaires. The SCARED was administered to a community sample of 1,508 children aged between 8 and 12 years. The sample was randomly split using half for the exploratory analysis and the other half for the confirmatory study. Furthermore a reduced version of the SCARED was developed using the SchmidLeiman procedure. Exploratory Factor Analysis yielded a four factor structure comprised of Somatic/panic, Generalized anxiety, Separation anxiety and Social phobia factors This structure was confirmed using Confirmatory Factor Analysis. The four factors, the full scale and the short scale showed good reliabilities. The results obtained seem to indicate that the Spanish version of the SCARED has good internal consistency, and along with other recent results, has a structure of four related factors that replicates the dimensions proposed for anxiety disorders by the DSM-IV-TR