scholarly journals Subsampling Intervals in Autoregressive Models with Linear Time Trend

Econometrica ◽  
2001 ◽  
Vol 69 (5) ◽  
pp. 1283-1314 ◽  
Author(s):  
Joseph P. Romano ◽  
Michael Wolf
Keyword(s):  
Time Trend ◽  
Linear Time ◽  
Autoregressive Models ◽  
Linear Time Trend

scholarly journals Study the Trend Pattern in COVID-19 using Spline-Based Time Series Model: A Bayesian Paradigm

2020 ◽  
Author(s):  
Varun Agiwal ◽  
Jitendra Kumar ◽  
Yau Chun Yip
Keyword(s):  
Time Series ◽  
Time Trend ◽  
Spline Function ◽  
Linear Time ◽  
Linear Trend ◽  
Model Parameters ◽  
Linear Pattern ◽  
Linear Time Trend ◽  
Proposed Model ◽  
Non Linear

A vast majority of the countries is under the economic and health crises due to the current epidemic of coronavirus disease 2019 (COVID-19). The present study analyzes the COVID-19 using time series, which is an essential gizmo for knowing the enlargement of infection and its changing behavior, especially the trending model. We have considered an autoregressive model with a non-linear time trend component that approximately converted into the linear trend using the spline function. The spline function split the COVID-19 series into different piecewise segments between respective knots and fitted the linear time trend. First, we obtain the number of knots with its locations in the COVID-19 series and then the estimation of the best-fitted model parameters are determined under Bayesian setup. The results advocate that the proposed model/methodology is a useful procedure to convert the non-linear time trend into a linear pattern of newly coronavirus case for various countries in the pandemic situation of COVID-19.

Trends in cigarette consumption and time to first cigarette on awakening from 2002 to 2015 in the USA: new insights into the ongoing tobacco epidemic

2017 ◽  
Vol 27 (4) ◽  
pp. 379-384 ◽  
Author(s):  
Renee D Goodwin ◽  
Melanie M Wall ◽  
Misato Gbedemah ◽  
Mei-Chen Hu ◽  
Andrea H Weinberger ◽  
...  
Keyword(s):  
Time Trend ◽  
Linear Time ◽  
Household Survey ◽  
Cross Sectional Study ◽  
Cigarette Consumption ◽  
Cross Sectional ◽  
Trend Analyses ◽  
Linear Time Trend ◽  
The Usa ◽  
Tobacco Epidemic

ObjectiveThe current study estimates trends in the number of cigarettes smoked per day (CPD) and percentage of smokers having their first CPD within 30 min of waking (time to first cigarette (TTFC)<30 min) among smokers from 2002 to 2015 in the USA overall, and adjusting for demographics. Trends in TTFC<30 min were also estimated by varying levels of cigarette consumption.MethodsData were drawn from the National Household Survey on Drug Use, an annual nationally representative cross-sectional study of the US population aged 12 and older (n=54 079–58 397 per year). Linear time trend analyses of CPD and TTFC<30 min were conducted adjusting for age, gender and income; linear time trend analyses of TTFC among those at varying levels of CPD were then performed.ResultsEstimates suggest that CPD declined overall from 2002 to 2015, and that the prevalence of TTFC<30 min declined overall among smokers (p<0.0001). The proportion of smokers consuming fewer (ie, 1–5, 6–15) CPD has increased while the number consuming 16+ CPD has decreased overall. Among those smoking 1–5 (p=0.0006) and 6–15 (p<0.0001) CPD, TTFC<30 min has increased significantly, but TTFC<30 min has remained unchanged among those smoking 16 or more CPD (p=0.5838).ConclusionsFindings suggest that smokers today are consuming fewer CPD, yet are increasingly likely to have their first cigarette earlier on awakening than they were a decade ago. Intervention and outreach efforts aimed at moving the prevalence lower may benefit from evaluating and addressing nicotine dependence even among lighter smokers.

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