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As transit ridership continues to fall in many cities across the globe, key policy debates continue around whether Uber and other ride-hailing services contribute to this trend. This research explores the effects of ride-hailing to Colombian cities on public transportation ridership using Uber's timeline as a case study. We test the hypothesis that ride-hailing may substitute or compete with public transit, particularly in cities with significant transit service gaps in coverage or quality. Our analysis builds on historic transit ridership data from national authorities and uses a staggered difference-in-difference model that accounts for fixed effects, seasonality, socioeconomic controls, and the presence of integrated transport systems. Despite significant reductions in transit ridership in most cities, our results suggest that Uber is not statistically associated with the observed drop in ridership. Moreover, consistent with evidence from previous research, public transit reforms implemented between 2007 and 2015 throughout Colombian cities appear to have contributed substantially to the declines in transit ridership observed across the country. Findings in this paper inform policy-targeted insights and contribute to current debates of the links between ride-hailing and public transit in Latin American cities.

En cuanto al efecto de la geografía en el comportamiento socialmente violento, este estudio introduce la idea de que la fragmentación geográfica está asociada con más terrorismo, dada su cercana relación con el role del gobierno y las condiciones socioeconómicas de las personas. Nosotros consideramos un panel de 128 países entre 1971 y 2005 usando metodologías para datos de conteo. Esto nos permite proveer evidencia robusta de un efecto consistente, incluso cuando diferentes controles son incluidos. Nuestra estimación de referencia indica que un país 1% más geográficamente fragmentado es asociado con un incremento de 1.38 en el promedio de número de ataques terroristas., Regarding the effect of geography on social violent behavior, this study introduces the idea that Geographic Fragmentation is associated with more terrorism, given its close relationship with the role of the government and socioeconomic conditions of people. We consider a panel of 128 countries between 1971 and 2005 using count data methodologies. This allows us to provide robust evidence for a consistent effect, even when different controls are included. Our baseline estimate indicates that one country with a 1% higher measure of Geographic Fragmentation is associated with an increment of 1.38 in the number of terrorist attacks on average.

El objetivo de esta investigación es pilotear y evaluar la introducción de innovaciones didácticas para un mejor aprendizaje en un curso general de microeconomía para estudiantes de pregrado. La evaluación se basa en la teoría de la autodeterminación y las metodologías centradas en el estudiante (SDT) (Deci y Ryan, 1985; Deci et al., 1991a), que señalan la motivación individual como crucial para el aprendizaje. El piloto del instrumento fue implementado con una muestra de 323 alumnos agrupados en 14 clases, demostrando que el problema más relevante del curso es que los estudiantes no sienten que lo que están aprendiendo es realmente útil en sus profesiones específicas, a pesar de que que están de acuerdo con la importancia de conocer estos temas. Este piloto nos permitió validar el instrumento utilizado que implementa dos escalas psicométricas: Escalas de transferencia de conocimiento y autodeterminación. La evaluación de impacto fue implementada para una muestra de 204 estudiantes, distribuidos en grupos tratados y control. La asignación de los estudiantes al tratamiento es aleatoria. Los resultados proporcionan evidencia de que la intervención mejora significativamente la motivación autodeterminada, así como el rendimiento académico de los estudiantes, aunque en una magnitud modesta., The objective of this research is piloting and evaluating the introduction of teaching innovations for better learning in a general microeconomics course for undergraduate students. The assessment is based on the Self Determination The- ory and student-centered methodologies (SDT)(Deci and Ryan, 1985; Deci et al., 1991a), which remark the individual motivation as crucial for learning. The pilot- ing of the instrument was implemented with a sample of 323 students grouped into 14 classes, giving evidence that the most relevant course problem is that students do not feel that what they are learning is really useful in their specific professions, despite the fact that they agree with the importance to know about such topics. This piloting allowed us to validate the used instrument which implements two psy- chometric scales: Knowledge transfer and self-determination scales. The impact evaluation was implemented for a sample of 204 students, distributed in treated and control groups. The assignment of students to treatment is random. Results provide evidence that the intervention significantly improves the self-determined motivation as well as the academic performance of students, although in a modest magnitude.