121 documents found, page 1 of 13
Time series clustering of air quality monitoring stations: the study case of th...
Cossa, Gabriel Chicale; Costa, Marco; Gonçalves, A. ManuelaSince air pollution is a major public health concern, collecting and analyzing air quality indicators data is very important for monitoring pollution. Data on these indicators are generally collected through air quality monitoring stations located in specific areas. In this study, 12 monitoring sites belonging to the Beijing Municipal Environmental Monitoring Center air pollution monitoring network are clustere...
Predictive accuracy of time series models applied to economic data: the Europea...
Lima, S.; Gonçalves, A. M.; Costa, MarcoModeling and accurately forecasting trend and seasonal patterns of a time series is a crucial activity in economics. The main propose of this study is to evaluate and compare the performance of three traditional forecasting methods, namely the ARIMA models and their extensions, the classical decomposition time series associated with multiple linear regression models with correlated errors, and the Holt?Winters ...
Bootstrapping state-space models: distribution-free estimation in view of predi...
Lima, José Francisco; Pereira, Fernanda Catarina; Gonçalves, Arminda Manuela; Costa, MarcoLinear models, seasonal autoregressive integrated moving average (SARIMA) models, and state-space models have been widely adopted to model and forecast economic data. While modeling using linear models and SARIMA models is well established in the literature, modeling using state-space models has been extended with the proposal of alternative estimation methods to the maximum likelihood. However, maximum likelih...
An Exploration of Blood-Based Biomarkers of Negative Symptoms of Psychosis in Men.
Rodrigues, Alexandra; Santos, Henrique Castro; Ferreira, Sara; Diogo, Vasco; Costa, Marco; Brissos, Sofia; Gama Marques, João; Prata, DianaNegative symptoms in the context of psychosis are still poorly understood and diagnosed, which impairs the treatment efficacy of current therapies and patient's integration in society. In this study, we aimed to test hypothesis-based and exploratory associations of negative symptom domains, as defined by the Brief Negative Symptom Scale (BNSS), with hormonal and hematological variables, and, complementarily, wi...
Assessment of distance to primary percutaneous coronary intervention centres in...
Borges-Rosa, João; Oliveira-Santos, Manuel; Simões, Marco A.; Carvalho, Paulo; Ibanez-Sanchez, Gema; Fernandez-Llatas, Carlos; Costa, MarcoObjectives: In ST-segment elevation myocardial infarction (STEMI), time delay between symptom onset and treatment is critical to improve outcome. The expected transport delay between patient location and percutaneous coronary intervention (PCI) centre is paramount for choosing the adequate reperfusion therapy. The “Centro” region of Portugal has heterogeneity in PCI assess due to geographical reasons. We aimed ...
Meteorological time series: an exploratory statistical and critical analysis
Gonçalves, A. Manuela; Pereira, F. Catarina; Costa, Marco; Leão, Celina PintoIncreasingly, reduction of water availability has been a reality, and population growth, pollution, and climate change have contributed to exacerbating this problem. Dry periods, which occur when precipitation is lower than expected in a given territory, have become more frequent and prolonged, and therefore it is crucial to efficiently manage water use in response to environmental concerns. The main challenge ...
Improving predictive accuracy in the context of dynamic modelling of non-statio...
Pereira, Fernanda Catarina; Gonçalves, A. Manuela; Costa, MarcoMost real time series exhibit certain characteristics that make the choice of model and its specification difficult. The objective of this study is to address the problem of parameter estimation and the accuracy of forecasts k-steps ahead in non-stationary time series with outliers in the context of state-space models. In this paper, three methods for detecting and treating outliers are proposed. We also presen...
Short-term forecast improvement of maximum temperature by state-space model app...
Pereira, F. Catarina; Gonçalves, A. Manuela; Costa, MarcoIn the context of "TO CHAIR'' project, this work aims to improve the accuracy of short-term forecasts of maximum air temperature obtained from the https://weatherstack.com/ website. The proposed methodology is based on a state-space representation that incorporates the latent process, the state, which is estimated recursively using the Kalman filter. The proposed model linearly and stochastically relates the fo...
Meteorological time series: an exploratory statistical and critical analysis
Gonçalves, A. Manuela; Pereira, F. Catarina; Costa, Marco; Leão, Celina P.Increasingly, reduction of water availability has been a real- ity, and population growth, pollution, and climate change have con- tributed to exacerbating this problem. Dry periods, which occur when precipitation is lower than expected in a given territory, have become more frequent and prolonged, and therefore it is crucial to efficiently manage water use in response to environmental concerns. The main chal- ...
Short-term forecast improvement of maximum temperature by state-space model app...
Pereira, F. Catarina; Gonçalves, A. Manuela; Costa, MarcoIn the context of “TO CHAIR” project, this work aims to improve the accuracy of short-term forecasts of maximum air temperature obtained from the https://weatherstack.com/website. The proposed methodology is based on a state-space representation that incorporates the latent process, the state, which is estimated recursively using the Kalman filter. The proposed model linearly and stochastically relates the fore...