scholarly journals Prediction of confirmed and death cases of Covid-19 in Chile through time series techniques: A comparative study

2021 ◽  
Author(s):  
Claudia Barría-Sandoval ◽  
Guillermo Ferreira ◽  
Katherine Benz-Parra ◽  
Pablo López-Flores
Keyword(s):  
Time Series ◽  
Moving Average ◽  
National Level ◽  
Time Dependent ◽  
Arima Models ◽  
Data Set ◽  
Counting Data ◽  
The Social ◽  
Organic Failure ◽  
Effective Public Health

Abstract(1)BackgroundChile has become one of the countries most affected by Covid-19, a pandemic that has generated a large number of cases worldwide, which if not detected and treated in time can cause multi-organic failure and even death. The social determinants of health such as education, work, social security, housing, environment, support networks and social cohesion are important aspects to consider for the control and intervention of this pathology. Therefore, it is essential to have information about the progress of the infections at the national level and thus apply effective public health interventions. In this paper, we compare different time series methodologies to predict the number of confirmed cases and deaths from Covid-19 in Chile and thus support the decisions of health agencies;(2)MethodsWe modeled the confirmed cases and deaths from Covid-19 in Chile by using ARIMA models, exponential smoothing techniques, Poisson models for time-dependent counting data. In addition, we evaluated the accuracy of the predictions by using a training set and test set;(3)ResultsThe database used in this paper allows us to say that for the confirmed Covid-19 cases the best model corresponds to a well-known Autoregressive Integrated Moving Average (ARIMA) time-series model, whereas for deaths from Covid-19 in Chile the best model resulted in damped trend method;(4)ConclusionARIMA models are an alternative to model the behavior of the spread of Covid19, however, and depending on the characteristics of the data set, other methodologies can better capture the behavior of these records, for example, Holt-winter’s method and time-dependent counting models.

scholarly journals Studying monthly rainfall over Dibrugarh, Assam: Use of SARIMA approach

MAUSAM ◽  
2021 ◽  
Vol 68 (2) ◽  
pp. 349-356
Author(s):  
J. HAZARIKA ◽  
B. PATHAK ◽  
A. N. PATOWARY
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
Moving Average ◽  
Demand Management ◽  
Arima Model ◽  
Monthly Rainfall ◽  
Series Data ◽  
Data Set ◽  
Modeling And Forecasting ◽  
Moving Average Model

Perceptive the rainfall pattern is tough for the solution of several regional environmental issues of water resources management, with implications for agriculture, climate change, and natural calamity such as floods and droughts. Statistical computing, modeling and forecasting data are key instruments for studying these patterns. The study of time series analysis and forecasting has become a major tool in different applications in hydrology and environmental fields. Among the most effective approaches for analyzing time series data is the ARIMA (Autoregressive Integrated Moving Average) model introduced by Box and Jenkins. In this study, an attempt has been made to use Box-Jenkins methodology to build ARIMA model for monthly rainfall data taken from Dibrugarh for the period of 1980- 2014 with a total of 420 points.  We investigated and found that ARIMA (0, 0, 0) (0, 1, 1)12 model is suitable for the given data set. As such this model can be used to forecast the pattern of monthly rainfall for the upcoming years, which can help the decision makers to establish priorities in terms of agricultural, flood, water demand management etc.  

Forecasting Software Vulnerabilities Using Time-Series Techniques

2019 ◽  
pp. 125-165
Author(s):  
Baidyanath Biswas
Keyword(s):  
Time Series ◽  
Homeland Security ◽  
Moving Average ◽  
Primary Objective ◽  
Data Set ◽  
Software Vulnerabilities ◽  
Systems Security ◽  
Univariate Time Series ◽  
Efficient Prediction ◽  
Best Fit

This chapter discusses the concepts of time-series applications and forecasting in the context of information systems security. The primary objective in such formulation is the training of the models followed by efficient prediction. Although economic and financial forecasting problems extensively use time-series, predicting software vulnerabilities is a novel idea. The chapter also provides appropriate guidelines for the implementation and adaptation of univariate time-series for information security. To achieve this, the authors focus on the following techniques: autoregressive (AR), moving average (MA), autoregressive integrated moving average (ARIMA), and exponential smoothing. The analysis considers a unique data set consisting of the publicly exposed software vulnerabilities, available from the U.S. Dept. of Homeland Security. The problem is presented first, followed by a general framework to identify the problem, estimate the best-fit parameters of that model, and conclude with an illustrative example from the above dataset to familiarize readers with the business problem.

scholarly journals On the Characterization and Forecasting of Ground Displacements of Ocean-Reclaimed Lands

2020 ◽  
Vol 12 (18) ◽  
pp. 2971
Author(s):  
Jingzhao Ding ◽  
Qing Zhao ◽  
Maochuan Tang ◽  
Fabiana Calò ◽  
Virginia Zamparelli ◽  
...  
Keyword(s):  
Time Series ◽  
Ground Deformation ◽  
Proper Time ◽  
Global Climate ◽  
Time Dependent ◽  
Ground Displacement ◽  
Data Set ◽  
Future Evolution ◽  
Adopted Model ◽  
Sar Data

In this work, we study ground deformation of ocean-reclaimed platforms as retrieved from interferometric synthetic aperture radar (InSAR) analyses. We investigate, in particular, the suitability and accuracy of some time-dependent models used to characterize and foresee the present and future evolution of ground deformation of the coastal lands. Previous investigations, carried out by the authors of this paper and other scholars, related to the zone of the ocean-reclaimed lands of Shanghai, have already shown that ocean-reclaimed lands are subject to subside (i.e., the ground is subject to settling down due to soil consolidation and compression), and the temporal evolution of that deformation follows a certain predictable model. Specifically, two time-gapped SAR datasets composed of the images collected by the ENVISAT ASAR (ENV) from 2007 to 2010 and the COSMO-SkyMed (CSK) sensors, available from 2013 to 2016, were used to generate long-term ground displacement time-series using a proper time-dependent geotechnical model. In this work, we use a third SAR data set consisting of Radarsat-2 (RST-2) acquisitions collected from 2012 to 2016 to further corroborate the validity of that model. As a result, we verified with the new RST-2 data, partially covering the gap between the ENV and CSK acquisitions, that the adopted model fits the data and that the model is suitable to perform future projections. Furthermore, we extended these analyses to the area of Pearl River Delta (PRD) and the city of Shenzhen, China. Our study aims to investigate the suitability of different time-dependent ground deformation models relying on the different geophysical conditions in the two areas of Shanghai and Shenzhen, China. To this aim, three sets of SAR data, collected by the ENV platform (from both ascending and descending orbits) and the Sentinel-1A (S1A) sensor (on ascending orbits), were used to obtain the ground displacement time-series of the Shenzhen city and its surrounding region. Multi-orbit InSAR data products were also combined to discriminate the up–down (subsidence) ground deformation time-series of the coherent points, which are then used to estimate the parameters of the models adopted to foresee the future evolution of the land-reclaimed ground consolidation procedure. The exploitation of the obtained geospatial data and products are helpful for the continuous monitoring of coastal environments and the evaluation of the socio-economical impacts of human activities and global climate change.

scholarly journals ARIMA Time Series Models for Full Truckload Transportation Prices

Forecasting ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 121-134 ◽  
Author(s):  
Jason W. Miller
Keyword(s):  
Time Series ◽  
Moving Average ◽  
The United States ◽  
Arima Models ◽  
Autoregressive Integrated Moving Average ◽  
Estimated Parameters ◽  
Coefficients Of Variation ◽  
Labor Statistics ◽  
Bureau Of Labor Statistics ◽  
Practical Implications

The trucking sector in the United States is a $700 billion plus a year industry and represents a large percentage of many firms’ logistics spend. Consequently, there is interest in accurately forecasting prices for truck transportation. This manuscript utilizes the autoregressive integrated moving average (ARIMA) methodology to develop forecasts for three time series of monthly archival trucking prices obtained from two public sources—the Bureau of Labor Statistics (BLS) and Truckstop.com. BLS data cover January 2005 through August 2018; Truckstop.com data cover January 2015 through August 2018. Different ARIMA models closely approximate the observed data, with coefficients of variation of the root mean-square deviations being 0.007, 0.040, and 0.048. Furthermore, the estimated parameters map well onto dynamics known to operate in the industry, especially for data collected by the BLS. Theoretical and practical implications of these findings are discussed.

scholarly journals First intercalibration of column-averaged methane from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change

2012 ◽  
Vol 5 (1) ◽  
pp. 1355-1379
Author(s):  
F. Forster ◽  
R. Sussmann ◽  
M. Rettinger ◽  
N. M. Deutscher ◽  
D. W. T. Griffith ◽  
...  
Keyword(s):  
Time Series ◽  
Near Infrared ◽  
Calibration Factor ◽  
Time Dependent ◽  
Total Carbon ◽  
Atmospheric Composition ◽  
Composition Change ◽  
Data Set ◽  
The Difference ◽  
Difference Time

Abstract. We present the intercalibration of dry-air column-averaged mole fractions of methane (XCH4) retrieved from solar FTIR measurements of the Network for the Detection of Atmospheric Composition Change (NDACC) in the mid-infrared (MIR) versus near-infrared (NIR) soundings from the Total Carbon Column Observing Network (TCCON). The study uses multi-annual quasi-coincident MIR and NIR measurements from the stations Garmisch, Germany (47.48° N, 11.06° E, 743 m a.s.l.) and Wollongong, Australia (34.41° S, 150.88° E, 30 m a.s.l.). Direct comparison of the retrieved MIR and NIR time series shows a phase shift in XCH4 seasonality, i.e. a significant time-dependent bias leading to a standard deviation (stdv) of the difference time series (NIR-MIR) of 8.4 ppb. After eliminating differences in a prioris by using ACTM-simulated profiles as a common prior, the seasonalities of the (corrected) MIR and NIR time series agree within the noise (stdv = 5.2 ppb for the difference time series). The difference time series (NIR-MIR) do not show a significant trend. Therefore it is possible to use a simple scaling factor for the intercalibration without a time-dependent linear or seasonal component. Using the Garmisch and Wollongong data together, we obtain an overall calibration factor MIR/NIR = 0.9926(18). The individual calibration factors per station are 0.9940(14) for Garmisch and 0.9893(40) for Wollongong. They agree within their error bars with the overall calibration factor which can therefore be used for both stations. Our results suggest that after applying the proposed intercalibration concept to all stations performing both NIR and MIR measurements, it should be possible to obtain one refined overall intercalibration factor for the two networks. This would allow to set up a harmonized NDACC and TCCON XCH4 data set which can be exploited for joint trend studies, satellite validation, or the inverse modeling of sources and sinks.

scholarly journals Multi-scale CO2

2021 ◽  
Author(s):  
Xiaomeng Gu ◽  
Andrew Viggo Metcalfe ◽  
Gary Glonek
Keyword(s):  
Time Series ◽  
Seasonal Variation ◽  
Industrial Revolution ◽  
Moving Average ◽  
Arima Models ◽  
Arma Models ◽  
Deterministic Models ◽  
Increasing Trend ◽  
Exponential Trend ◽  
Sampling Intervals

Abstract Five time series of estimated atmospheric CO 2 with sampling intervals ranging from 0.5 million years to the relatively high frequency of one week are analysed. The yearly series shows a clear increasing trend since the beginning of the first Industrial Revolution around 1760. The weekly series shows a clear increasing trend and also seasonal variation. In both cases, the trend is fitted by a conceptual model that consists of a baseline value with an exponential trend superimposed. For the weekly series, the seasonal variation is modelled as an exponential of a sum of sine and cosine terms. The deviations from these deterministic models are treated as detrended and deseasonalised time series.Then,threesub-categoriesof autoregressive integrated moving average (ARIMA) models are fitted to the five time series: ARMA models which are stationary; FARIMA models which are stationary but have long memory and are fractal processes, and ARIMA models which are variations on a random walk and so non-stationary in the variance.The FARIMA and ARIMA models provide better fits to the data than the corresponding ARMA models. All the fitted models are close to the boundary of stability, and are consistent with claims that climate change due to an increase in atmospheric CO 2 may not quickly be reversed even if CO 2 emissions are stopped.

scholarly journals Influent Forecasting for Wastewater Treatment Plants in North America

2019 ◽  
Vol 11 (6) ◽  
pp. 1764 ◽  
Author(s):  
Gavin Boyd ◽  
Dain Na ◽  
Zhong Li ◽  
Spencer Snowling ◽  
Qianqian Zhang ◽  
...  
Keyword(s):  
Time Series ◽  
Wastewater Treatment ◽  
North America ◽  
Wastewater Treatment Plants ◽  
Moving Average ◽  
Wastewater Management ◽  
Sufficient Information ◽  
Arima Models ◽  
Analysis Model ◽  
Influent Flow

Autoregressive Integrated Moving Average (ARIMA) is a time series analysis model that can be dated back to 1955. It has been used in many different fields of study to analyze time series and forecast future data points; however, it has not been widely used to forecast daily wastewater influent flow. The objective of this study is to explore the possibility for wastewater treatment plants (WWTPs) to utilize ARIMA for daily influent flow forecasting. To pursue the objective confidently, five stations across North America are used to validate ARIMA’s performance. These stations include Woodward, Niagara, North Davis, and two confidential plants. The results demonstrate that ARIMA models can produce satisfactory daily influent flow forecasts. Considering the results of this study, ARIMA models could provide the operating engineers at both municipal and rural WWTPs with sufficient information to run the stations efficiently and thus, support wastewater management and planning at various levels within a watershed.

Predicting catch per unit effort from a multispecies commercial fishery in Port Phillip Bay, Australia

2020 ◽  
Vol 71 (4) ◽  
pp. 542
Author(s):  
Karina L. Ryan ◽  
Denny Meyer
Keyword(s):  
Time Series ◽  
Environmental Conditions ◽  
Environmental Variability ◽  
Moving Average ◽  
Commercial Fishing ◽  
Arima Models ◽  
Catch Per Unit Effort ◽  
Explanatory Variables ◽  
Unit Effort ◽  
Stock Abundance

Quantitative models that predict stock abundance can inform stock assessments and adaptive management that allows for less stringent controls when abundance is high and environmental conditions are suitable, or tightening controls when abundance is low and environmental conditions are least suitable. Absolute estimates of stock abundance are difficult and expensive to obtain, but data from routine reporting in commercial fisheries logbooks can provide an indicator of stock status. Autoregressive integrated moving average (ARIMA) models were constructed using catch per unit effort (CPUE) from commercial fishing in Port Phillip Bay from 1978–79 to 2009–10. Univariate and multivariate models were compared for short-lived species (Sepioteuthis australis), and species represented by 1–2 year-classes (Sillaginodes punctatus) and 5–6 year-classes (Chrysophrys auratus). Simple transfer models incorporating environmental variables produced the best predictive models for all species. Multivariate ARIMA models are dependent on the availability of an appropriate time series of explanatory variables. This study demonstrates an application of time series methods to predict monthly CPUE that is relevant to fisheries for species that are short lived or vulnerable to fishing during short phases in their life history or where high intra-annual variation in stock abundance occurs through environmental variability.

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