time series studies
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2021 ◽  
Author(s):  
Duleeka Kniipe ◽  
Ann John ◽  
Prianka Padmanathan ◽  
Emily Eyles ◽  
Dana Dekel ◽  
...  

There is widespread concern over the potential impact of the COVID-19 pandemic on suicide and self-harm globally, particularly in low- and middle-income countries (LMIC) where the burden of these behaviours is greatest. We synthesised the evidence from the published literature on the impact of the pandemic on suicide and self-harm in LMIC. This review is nested within a living systematic review that continuously identifies published evidence (all languages) through a comprehensive automated search of multiple databases (PubMed; Scopus; medRxiv, PsyArXiv; SocArXiv; bioRxiv; the WHO COVID-19 database; and the COVID-19 Open Research Dataset by Semantic Scholar (up to 11/2020), including data from Microsoft Academic, Elsevier, arXiv and PubMed Central.) All articles identified by the 4th August 2021 were screened. Papers reporting on data from a LMIC and presenting evidence on the impact of the pandemic on suicide or self-harm were included. A total of 22 studies from LMIC were identified representing data from 12 countries. There was an absence of data from Africa. The reviewed studies mostly report on the early months of COVID-19 and were generally methodologically poor. Few studies directly assessed the impact of the pandemic. The most robust evidence, from time-series studies, indicate either a reduction or no change in suicide and self-harm behaviour. As LMIC continue to experience repeated waves of the virus and increased associated mortality, against a backdrop of vaccine inaccessibility and limited welfare support, continued efforts are needed to track the indirect impact of the pandemic on suicide and self-harm in these countries.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Simon L. Turner ◽  
Andrew B. Forbes ◽  
Amalia Karahalios ◽  
Monica Taljaard ◽  
Joanne E. McKenzie

Abstract Background Interrupted time series (ITS) studies are frequently used to evaluate the effects of population-level interventions or exposures. However, examination of the performance of statistical methods for this design has received relatively little attention. Methods We simulated continuous data to compare the performance of a set of statistical methods under a range of scenarios which included different level and slope changes, varying lengths of series and magnitudes of lag-1 autocorrelation. We also examined the performance of the Durbin-Watson (DW) test for detecting autocorrelation. Results All methods yielded unbiased estimates of the level and slope changes over all scenarios. The magnitude of autocorrelation was underestimated by all methods, however, restricted maximum likelihood (REML) yielded the least biased estimates. Underestimation of autocorrelation led to standard errors that were too small and coverage less than the nominal 95%. All methods performed better with longer time series, except for ordinary least squares (OLS) in the presence of autocorrelation and Newey-West for high values of autocorrelation. The DW test for the presence of autocorrelation performed poorly except for long series and large autocorrelation. Conclusions From the methods evaluated, OLS was the preferred method in series with fewer than 12 points, while in longer series, REML was preferred. The DW test should not be relied upon to detect autocorrelation, except when the series is long. Care is needed when interpreting results from all methods, given confidence intervals will generally be too narrow. Further research is required to develop better performing methods for ITS, especially for short series.


2021 ◽  
pp. 69-87
Author(s):  
Emily F. Rothman

This chapter reviews the results of ecological time-series studies, experimental studies, case-control studies, and meta-analyses of the relationship between pornography viewing and aggression perpetration. Antisocial personality characteristics can increase the risk that a subset of pornography viewers will engage in sexually aggressive behavior subsequent to pornography exposure. Public health professionals may be invited to play a role in policy decision-making that balances the public’s right to sexually explicit material against the risk that some viewers may be activated by viewing violent-looking pornography.


2021 ◽  
Vol 13 (17) ◽  
pp. 3349
Author(s):  
Chuiqing Zeng ◽  
Caren E. Binding

Envisat’s MERIS and its successor Sentinel OLCI have proven invaluable for documenting algal bloom conditions in coastal and inland waters. Observations over turbid eutrophic waters, in particular, have benefited from the band at 708 nm, which captures the reflectance peak associated with intense algal blooms and is key to line-height algorithms such as the Maximum Chlorophyll Index (MCI). With the MERIS mission ending in early 2012 and OLCI launched in 2016, however, time-series studies relying on these two sensors have to contend with an observation gap spanning four years. Alternate sensors, such as MODIS Aqua, offering neither the same spectral band configuration nor consistent spatial resolution, present challenges in ensuring continuity in derived bloom products. This study explores a neural network (NN) solution to fill the observation gap between MERIS and OLCI with MODIS Aqua data, delivering consistent algal bloom spatial extent products from 2002 to 2020 using these three sensors. With 14 bands of MODIS level 2 partially atmospherically corrected spectral reflectance as the NN input, the missing MERIS/OLCI band at 708 nm required for the MCI is simulated. The resulting NN-derived MODIS MCI (NNMCI) is shown to be in good agreement with MERIS and OLCI MCI in 2011 and 2017 respectively over the western basin of Lake Erie (R2 = 0.84, RMSE = 0.0032). To overcome the impact of MODIS sensor saturation over bright water targets, which otherwise renders pixels unusable for bloom detection using R-NIR wavebands, a variant NN model is employed which uses the 9 MODIS bands with the lowest probability of saturation to simulate the MCI. This variant NN predicts MCI with only a small increase in uncertainty (R2 = 0.73, RMSE = 0.005) allowing reliable estimates of bloom conditions in those previously unreported pixels. The NNMCI is shown to be robust when applied beyond the initial training dataset on Lake Erie, and when re-trained on different geographic areas (Lake Winnipeg and Lake of the Woods). Despite differences in spatial, temporal, and spectral resolution, MODIS algal bloom presence/absence was correctly classified in >92% of cases and bloom spatial extent derived within 25% uncertainty, allowing the application to the 2012–2015 time period to form a continuous and consistent multi-mission monitoring dataset from 2002 to 2020.


2021 ◽  
Author(s):  
Arvind K Shantharam ◽  
Amy Baco-Taylor

Submarine canyons are highly dynamic and productive ecosystems, but time-series studies of metazoan benthic communities in canyons are scarce. Deep-sea macrofauna from the DeSoto Canyon in the northern Gulf of Mexico were sampled annually from 2012 through 2014 from five stations within the Canyon and from two stations in 2013 and 2014 on the adjacent open slope, for analysis of interannual dynamics, temporal variability, and potential influence of the Deepwater Horizon oil spill (DwH), which occurred nearby in 2010. At a few sites, elevated abundance was observed at the start of the time-series for overall macrofauna and for deposit feeder abundance. However, diversity metrics showed no difference within stations among time points. Community and feeding guild structure varied by station, as expected, but showed no statistical difference among time points within a station. Some temporal variability was visible in temporal trajectory overlays. Cluster analyses showed grouping more by station than by time point. Metrics utilized for measuring potential oil contamination impact and overall community stress including the benthic polychaete/amphipod ratio, feeding guild abundance, macrofaunal indicators designed from the DwH, and community dispersion, generally exhibited a paucity of evidence of impact, both yearly and with site-to-site comparisons. This suggests low levels of impact in the canyon consistent with the low deposition of hydrocarbons, the timing of sampling, and quick recovery of canyon foraminifera. Taken together these results suggest relatively low levels of temporal variability within the DeSoto Canyon macrofauna with little evidence of oil influence on these sites within the studied time range.


Author(s):  
Yanqiu Yu ◽  
Joseph Tak Fai Lau ◽  
Mason M C Lau

Abstract Social and physical distancing is important in controlling the COVID-19 pandemic and it impacts people’s financial/social well-being tremendously. This study tested the application of the Theory of Planned Behaviors (TPB) to three types of social/physical distancing indicators (i.e., the number of close physical contacts on a single day in public venues, the frequencies of avoiding social gathering, and the levels of physical distancing in public venues). A population-based random telephone survey interviewed 300 Hong Kong Chinese adults in April 2020 when gatherings involving >4 people were banned. The participants on average made 15.3 close physical contacts (<1.5 m and for >3 min) in a day (5.0 in public transportation). About 80% practiced social distancing (avoided/reduced social gatherings) and physical distancing in public spaces (e.g., avoidance of going out, visiting crowded places, and gatherings of >4 people) but only 35.4% avoided using public transportations. Positive but not negative attitudes (inconvenience and lack of necessity), perceived behavioral control, and subjective norm were significantly associated with the three social/physical distancing outcomes. The data suggest that the levels of social/physical distancing were relatively high in the Hong Kong general population, and it, in general, supports the application of TPB to understand factors of social distancing for preventing COVID-19. Health promotion should take the findings into account. Furthermore, cross-cultural and time-series studies are warranted to compare the levels of social/physical distancing across countries and further explore their effectiveness in controlling the COVID-19 pandemic.


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