Time-series analysis as an important contemporary statistical tool

Estimating the COVID-19 prevalence and mortality using a novel data-driven hybrid model based on ensemble empirical mode decomposition

In this study, we proposed a new data-driven hybrid technique by integrating an ensemble empirical mode decomposition (EEMD), an autoregressive integrated moving average (ARIMA), with a nonlinear autoregressive artificial neural network (NARANN), called the EEMD-ARIMA-NARANN model, to perform time series modeling and forecasting based on the COVID-19 prevalence and mortality data from 28 February 2020 to 27 June 2020 in South Africa and Nigeria. By comparing the accuracy level of forecasting measurements with the basic ARIMA and NARANN models, it was shown that this novel data-driven hybrid model did a better job of capturing the dynamic changing trends of the target data than the others used in this work. Our proposed mixture technique can be deemed as a helpful policy-supportive tool to plan and provide medical supplies effectively. The overall confirmed cases and deaths were estimated to reach around 176,570 [95% uncertainty level (UL) 173,607 to 178,476] and 3454 (95% UL 3384 to 3487), respectively, in South Africa, along with 32,136 (95% UL 31,568 to 32,641) and 788 (95% UL 775 to 804) in Nigeria on 12 July 2020 using this data-driven EEMD-ARIMA-NARANN hybrid technique. The contributions of this study include three aspects. First, the proposed hybrid model can better capture the dynamic dependency characteristics compared with the individual models. Second, this new data-driven hybrid model is constructed in a more reasonable way relative to the traditional mixture model. Third, this proposed model may be generalized to estimate the epidemic patterns of COVID-19 in other regions.

Pharmaceutical sales of pseudoephedrine: the impact of electronic tracking systems on methamphetamine crime incidents

BACKGROUND AND AIMS

Electronic tracking systems (ETS) are used extensively in pharmacies across the United States and Australia to control suspicious sales of pseudoephedrine. This study measures the impact of one ETS-Project STOP-on the capacity of police to reduce production, supply and possession of methamphetamine.

DESIGN

Using official police data of incidents of production, supply and possession from January 1996 to December 2011 (n = 192 data points/months over 16 years), we used a quasi-experimental, time-series approach.

SETTING

The State of Queensland, Australia.

PARTICIPANTS

No individual participants are included in the study. The unit of analysis is reported police incidents.

MEASUREMENTS

The study examines the impact of the ETS on production (n = 5938 incidents), drug supply and trafficking (n = 20 094 incidents) and drug possession or use (n = 118 926) of methamphetamine.

FINDINGS

Introduction of the ETS in November 2005 was associated with an insignificant decrease (P = 0.15) in the production of methamphetamine. The intervention was associated with a statistically significant increase in supply incidents (P = 0.0001). There was no statistically significant effect on the incidence of possession (P = 0.59).

CONCLUSIONS

Electronic tracking systems can reduce the capacity of people to produce methamphetamine domestically, but seem unlikely to affect other aspects of the methamphetamine problem such as possession, distribution and importation.

Impacts of federal ephedrine and pseudoephedrine regulations on methamphetamine-related hospital admissions

AIMS

To determine whether the federal regulation of ephedrine and pseudoephedrine, precursors used in illicit methamphetamine production, reduced methamphetamine-related acute care hospital admissions.

DESIGN

ARIMA-intervention time-series analysis.

SETTING

California (1983-2000), Arizona and Nevada (1991-2000), USA.

MEASUREMENTS

Monthly counts of methamphetamine-related acute care hospital admissions.

INTERVENTIONS

Bulk powder ephedrine and pseudoephedrine: regulated November 1989. Products containing ephedrine as the single active medicinal ingredient: regulated August 1995. Products containing pseudoephedrine: regulated October 1997. Large-scale producers used ephedrine and pseudoephedrine in these forms. Ephedrine combined with other active medicinal ingredients (e.g. various cold medicines), used mainly by small-scale producers: regulated October 1996.

FINDINGS

In California, the bulk powder regulation stopped a 7-year rise in admissions (1983-89) and reduced them by 35% (P < 0.01). The single ingredient ephedrine regulation stopped a 4-year rise (1992-95) in California, Arizona and Nevada, with 48% (P < 0.01), 71% (P < 0.01) and 52% (P < 0.01) reductions, respectively. The pseudoephedrine products regulation stopped a 2-year rise (1996-97) in California, Arizona and Nevada, with 38% (P < 0.01), 41% (P < 0.05) and 61% (P < 0.01) reductions, respectively. Admissions rose at the end of the study period but were still well below peak 1990s levels. The regulation of ephedrine combined with other active medicinal ingredients had no significant impact in any of the three states.

CONCLUSIONS

Regulations targeting precursors used by large-scale producers reduced admissions substantially during the study period. However, the regulation of precursors used primarily by small-scale producers had little, if any, effect.