Papers by Daniel Ayala Obando
Bayesian Analysis, 2021
An explicit representation of phase-type distributions as an infinite mixture of Erlang distribut... more An explicit representation of phase-type distributions as an infinite mixture of Erlang distributions is introduced. The representation unveils a novel and useful connection between a class of Bayesian nonparametric mixture models and phase-type distributions. In particular, this sheds some light on two hot topics, estimation techniques for phase-type distributions, and the availability of closed-form expressions for some functionals related to Dirichlet process mixture models. The power of this connection is illustrated via a posterior inference algorithm to estimate phase-type distributions, avoiding some difficulties with the simulation of latent Markov jump processes, commonly encountered in phase-type Bayesian inference. On the other hand, closed-form expressions for functionals of Dirichlet process mixture models are illustrated with density and renewal function estimation, related to the optimal salmon weight distribution of an aquaculture study.
Revista De La Facultad De Ciencias, Jul 30, 2012
RESUMEN: Se estiman curvas típicas diarias para los contaminantes monóxido de carbono, dióxido de... more RESUMEN: Se estiman curvas típicas diarias para los contaminantes monóxido de carbono, dióxido de nitrógeno y ozono en los años 2003, 2004 y 2005 en la ciudad de Cali, mediante una técnica no paramétrica de suavización. Se estudia la evolución de las curvas comparándolas estadísticamente por medio de un análisis de covarianza no paramétrico, con el fin de identificar patrones y tendencias. Los resultados muestran que existe una reducción estadísticamente significativa de los niveles típicos de contaminación a través de los años. La información utilizada proviene de las estaciones de la red de monitoreo de calidad del aire en la ciudad.
Revista de Saúde Pública, 2020
OBJECTIVE: To analyze the nutritional situation of children under five years old from both urban ... more OBJECTIVE: To analyze the nutritional situation of children under five years old from both urban and rural areas of Colombia. METHOD: Analytical study, based on cross-sectional data, collected from ENSIN-2015. The sample consisted of 12,256 children aged between 0 and 4 years old. We calculated the prevalence ratios (PR) with their respective 95% confidence interval (95%CI). PR were assessed by binomial regression models with malnutrition or overweight as the dependent variable and geographic area as the explanatory variable. We used context variables to adjust the estimated PR and control the confounder within. RESULTS: Acute malnutrition (weight-for-height) had a prevalence of 1.6%, while overweight had a 5.6% rate. No differences per geographic zone in the weight-for-height indicator were found. Stunted growth – chronic malnutrition – was higher in the rural area (PR = 1.2; 95%CI 1–1.53; p = 0.050). Prevalences adjusted by variables related to structural, social and economic deve...
Revista de Saúde Pública
OBJECTIVE: To analyze the consumption of ultra-processed foods in the Colombian population across... more OBJECTIVE: To analyze the consumption of ultra-processed foods in the Colombian population across sociodemographic factors. METHODS: We used data from the 2005 National Survey of the Nutritional Status in Colombia. Food consumption was assessed using a 24-hour food recall in 38,643 individuals. The food items were classified according to the degree and extent of industrial processing using the NOVA classification. RESULTS: The mean calorie contribution of ultra-processed foods ranged from 0.2% in the lowest quintile of consumers to 41.1% in the highest quintile of consumers. The greatest increases were due to the consumption of industrialized breads, sweet and savory snacks, sugary drinks, processed meats, and confectionery. No major differences were found in the consumption of ultra-processed foods between men and women. We observed significant differences by age, socioeconomic status, area of residence, and geographic region. Children and adolescents showed a higher intake of ultr...
Lancet (London, England), Jan 19, 2016
International studies of the health of Indigenous and tribal peoples provide important public hea... more International studies of the health of Indigenous and tribal peoples provide important public health insights. Reliable data are required for the development of policy and health services. Previous studies document poorer outcomes for Indigenous peoples compared with benchmark populations, but have been restricted in their coverage of countries or the range of health indicators. Our objective is to describe the health and social status of Indigenous and tribal peoples relative to benchmark populations from a sample of countries. Collaborators with expertise in Indigenous health data systems were identified for each country. Data were obtained for population, life expectancy at birth, infant mortality, low and high birthweight, maternal mortality, nutritional status, educational attainment, and economic status. Data sources consisted of governmental data, data from non-governmental organisations such as UNICEF, and other research. Absolute and relative differences were calculated. Ou...
by Carlos E . A . Coimbra, Jr, James R Welch, Ricardo Ventura Santos, Chimaraoke Izugbara, Daniel Ayala Obando, Pedro Izugbara, Malcolm King, Martina Kamaka, Leslie Yap, Blas Armien, and Per Axelsson Background International studies of the health of Indigenous and tribal peoples provide important... more Background International studies of the health of Indigenous and tribal peoples provide important public health insights. Reliable data are required for the development of policy and health services. Previous studies document poorer outcomes for Indigenous peoples compared with benchmark populations, but have been restricted in their coverage of countries or the range of health indicators. Our objective is to describe the health and social status of Indigenous and tribal peoples relative to benchmark populations from a sample of countries.
Lancet (London, England), Jan 19, 2016
International studies of the health of Indigenous and tribal peoples provide important public hea... more International studies of the health of Indigenous and tribal peoples provide important public health insights. Reliable data are required for the development of policy and health services. Previous studies document poorer outcomes for Indigenous peoples compared with benchmark populations, but have been restricted in their coverage of countries or the range of health indicators. Our objective is to describe the health and social status of Indigenous and tribal peoples relative to benchmark populations from a sample of countries. Collaborators with expertise in Indigenous health data systems were identified for each country. Data were obtained for population, life expectancy at birth, infant mortality, low and high birthweight, maternal mortality, nutritional status, educational attainment, and economic status. Data sources consisted of governmental data, data from non-governmental organisations such as UNICEF, and other research. Absolute and relative differences were calculated. Ou...
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Papers by Daniel Ayala Obando