On the treatment of repeated observations in panel data: efficiency of mixed logit parameter estimates

Travel demand models are often estimated using cross-sectional data. Although the use of panel data has recently increased in many areas, there are still many aspects that have not been analyzed fully. Some examples of unexplored topics are: the optimal length of panel surveys and the resulting issue of how to model panel data correctly in the presence of repeated observations (for example, several trips per week, by people in a panel with waves every six months) and whether, and to what extent, this affects the efficiency of the estimated parameters and their capability to replicate the true situation. In this paper we analyse this issue and test the effect of including journeys made, with the same characteristics, several times in a week. A broad variety of models accounting for fixed parameters but also for random heterogeneity and correlation among individuals were estimated using each of real and synthetic data. The real data come from the Santiago Panel (2006-2008), while the synthetic data were appropriately generated to examine the same problem in a controlled experiment. Our results show that having more observations per individual increases the probability of capturing effects (different types of heterocedasticity), but having identical observations in a data panel reduces the capability to reproduce true phenomena. Consequently, the definition of panel survey duration requires us to consider the implicit level of routine that is present as represented in the proportion of identical observations

Inertia and shock effects on mode choice panel data: implications of the Transantiago implementation

The mode choice process, especially in the case of commuter trips, reflects the strong tendency people have to simplify the assessment of their options when confronted with successive well-known decisions. Thus, it is common to repeat the “habitual” choice over time involving a potentially important inertia element. However, while inertia effects increase the probability of maintaining the same choice in a stable situation, in a changing environment i.e. one that is disrupted by a radical or significant policy intervention, user behaviour may be affected by a specific response to abrupt changes. Shock effects of this kind could increase the probability of individuals leaving their habitual choices. Temporal effects have been commonly ignored in practical studies, as most demand models to date have been based on cross-sectional data. A few recent studies dealing with panel data have managed to incorporate inertia effects, but there are no studies that have included both inertia and shock effects. To address this, we started by building a data panel around the introduction of a new and radical policy for the conurbation of Santiago de Chile. The final aim was to develop mode choice models incorporating the effects of three main forces involved in the choice process: (1) the relative values of the modal attributes, (2) the inertia effect, and (3) the shock resulting from and abrupt policy intervention. This paper presents the formulation of an inertia-shock model and its application to each of simulated and real data. The results confirm that changing systems should be modelled respecting the presence of both inertia and shock effects, otherwise serious errors in model estimation may arise

Estimación cualitativa de la incertidumbre para el inventario de contaminantes tóxicos del aire del gran área metropolitana en el 2007

Los inventarios de contaminantes presentan un modelo general de cálculo, o estimación, asociado a la relación entre los datos de información obtenidos y los factores utilizados. Estos plantean, por sus características, niveles de incertidumbre asociados a dicho cálculo. La evaluación de las incertidumbres en inventarios es una temática abordada desde distintos aspectos dependiendo de la calidad de los datos, factores utilizados y estimaciones realizadas. El planteo de una estimación cualitativa permite, independientemente de la información utilizada, caracterizar las fortalezas y debilidades de las estimaciones realizadas. Se desarrolla una metodología básica para dicha estimación y se aplica la misma al Inventario de Contaminantes Tóxicos del Aire en el Gran Área Metropolitana de Costa Rica en el 2007, planteándose los resultados para este caso particular

Substituent Effects on B−N Bonding and Coupling Constants in Fivemembered Rings N3B2H4X and N2B3H4X, for X = H, F, and Li

Ab initio calculations have been carried out to investigate bonding patterns and B−N coupling constants in five-membered rings N3B2H4X and N2B3H4X, for X = H, F, and Li, with substitution occurring only at N. F-substitution results in the formation of a covalent N−F bond, whereas Li-substitution leads to an ion-pair with little covalency. Substitution has a highly localized effect, changing the electron density only at the substituted N. F-substitution also has a very localized effect on coupling constants, at most only changing 1J(B−N) involving the substituted N. Li-substitution has a more delocalized effect. It always decreases 1J(B−N) involving the substituted N, and may also decrease 1J(B−N) of a proximal B−N bond if the B atom is bonded to the substituted N

Endocranial morphology of Pygoscelis calderensis (Aves, Spheniscidae) from the Neogene of Chile and remarks on brain morphology in modern Pygoscelis

Fil: Paulina-Carabajal, Ariana. Museo Carmen Funes. Neuquen; ArgentinaFil: Acosta Hospitaleche, Carolina. División Paleontología Vertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Yury-Yáñez, Roberto E.. Laboratorio de Zoología de Vertebrados. Universidad de Chile; Chil

Effet de l’huile d’olive, de tournesol ou de graines de lin sur le patron de fermentation et la production de méthane dans le système de simulation ruminale RUSITEC

6 páginas, 2 tablas.-- Contributed to: 13th Seminar of the FAO-CIHEAM Sub-Network on Sheep and Goat Nutrition: Challenging strategies to promote sheep and goat sector in the current global (León, Spain, oct 14-16, 2009).The objective of this study was to investigate the effects of the addition of different vegetable oils to the diet on the fermentation pattern and methane production in Rusitec fermenters. For this purpose four treatments were randomly allocated to sixteen fermenters in a completely random design. Inoculum was obtained from four ruminally fistulated Merino sheep fed lucerne hay and concentrate. Treatments were defined by the diet supplied to the fermenters, so that the control treatment (C) diet was a total mixed ration for ewes on lactation. In the other experimental treatments the control diet was supplemented with olive oil (OO), sunflower oil (SO) or linseed oil (LO) to reach a final concentration of 50 g oil/kg diet. After 7 days of adaptation, samples of effluent, fermenters’ fluid content and digesta of each fermenter were collected during 10 days. There were no significant differences (P>0.05) between treatments in pH values in the fermenters’ fluid content. The LO diet showed (P0.05). All three oils reduced methane production compared with control cultures (P0.05) of oil supplementation on Llactate concentration. Ammonia N concentration was higher (P<0.05) in the control treatment, but there were no significant differences between treatments in microbial protein output. In conclusion, these results indicate that fermentation pattern is affected by oil supplementation mainly by decreasing the acetate to propionate ratio, as well as methane production.Funding received from Spanish MICINN (Projects AGL2008-04805 and AGL2005-04760) and from Junta de Castilla y León (Project GR158) is gratefully acknowledged.Peer Reviewe

Introduction : analysing English syntax past and present

This book is an exploration of categories, constructions, and change in English syntax. A great many books are published on the syntax of English, both monographs and edited volumes, and yet another may seem unnecessary. However, we felt more than justified in adding to the sizeable literature here for two reasons. The first, to borrow from Richard M. Hogg and David Denison’s justification for A History of the English Language, is that ‘one of the beauties of the language is its ability to show continuous change and flexibility while in some sense remaining the same

Gestión de la empresa Erie en simulador de negocios CAPSIM

El objetivo de este trabajo es documentar la estrategia, las decisiones y los resultados del equipo de trabajo que tomó la dirección de la compañía Erie en el simulador de negocios Capstone. En este simulador, que se especializa en la enseñanza de estrategias de negocios, compiten seis empresas durante ocho años de operación, está situado en la industria de los sensores y el año de arranque fue el 2017

Exploring Student Self-Assessment in General Education: A Pilot Study Using Surveying Tools

Title: Exploring Student Self-Assessment in General Education: A Pilot Study Using Surveying Tools Authors: Cristo Ernesto Yáñez León, James Lipuma, Yi Meng, Jeremy Reich Conference: Congreso Internacional de Investigación Academia Journals Tláhuac 2023 Venue: Instituto Tecnológico de Tláhuac II, CDMX, México Date: September 13-14, 2023. This research article delves into an innovative pilot study examining student self-assessment in the realm of General Education Requirements (GER) within a STEM-focused university. Employing a tailored survey based on AAC&U VALUE Rubrics and utilizing a 5-point Likert scale, the study contributes to the Middle States Commission on Higher Education (MSCHE) accreditation review. Our findings explore the congruence between self-assessed student awareness and institutional benchmarks, shedding light on the efficacy of out-of-course pre-and post-tests. The research unveils pivotal insights into student awareness and paves the way for inter-domain dialogue in educational assessment. This study serves as a crucial step toward improving institutional effectiveness in GER and broadens the application of self-assessment mechanisms across diverse educational settings.https://digitalcommons.njit.edu/stemresources/1055/thumbnail.jp

Magnetic multiwalled carbon nanotubes as nanocarrier tags for sensitive determination of fetuin in saliva

This paper reports the development and performance of an electrochemical immunosensor using magnetic multiwalled carbon nanotubes (m-MWCNTs) as nanocarrier tags for the determination of human fetuin A (HFA), a relevant biomarker of obesity, insulin resistance, and type-2 diabetes as well as for pancreatic and liver cancers and inflammatory processes. Screen-printed carbon electrodes were grafted with p-aminobezoic acid and streptavidin was covalently immobilized on the electrode surface. A biotinylated capture antibody was immobilized through streptavidin-biotin interaction and a sandwich assay configuration was implemented using m-MWCNTs conjugated with HRP and anti-HFA antibodies as the detection label. The determination of HFA was accomplished by measuring the current produced by the electrochemical reduction of benzoquinone at -200 mV upon addition of H2O2 as HRP substrate. The prepared m-MWCNTs were characterized by SEM, TEM, XRD and EDS. All the steps involved in the immunosensor preparation were monitored by electrochemical impedance spectroscopy and cyclic voltammetry. A linear calibration plot for HFA was found between 20 and 2000 pg/mL with a LOD value of 16 pg/mL. This performance is notably better than that reported for an ELISA kit and a chronoimpedimetric immunosensor. The favorable contribution of m-MWCNTs in comparison with MWCNTs without incorporated magnetic particles to this excellent analytical performance is also highlighted. The immunosensor selectivity against other proteins and potentially interfering compounds was excellent. In addition, the usefulness of the immunosensor was demonstrated by the analysis of HFA in saliva with minimal sample treatment