Impact of 65-mph Speed Limit on Iowa’s Rural Interstate Highways: Integrated Bayesian Forecasting and Dynamic Modeling Approach

1998 ◽  
Vol 1640 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Shanmuganathan Raju ◽  
Reginald Souleyrette ◽  
Thomas H. Maze
Keyword(s):  
Time Series ◽  
Dynamic Modeling ◽  
Speed Limit ◽  
Bayesian Forecasting ◽  
Modeling Approach ◽  
Surface Transportation ◽  
Before And After ◽  
Accident Data ◽  
Relocation Assistance ◽  
The Impact

In 1987, a provision of the Surface Transportation and Uniform Relocation Assistance Act allowed states to raise speed limits on rural Interstates to 65 mph (104.6 km/h). By 1995, nearly all states had done so. Several studies have investigated the safety impacts of these increases. Methodologies varied from analysis of variance to simple before and after comparison and have included time series procedures, with and without intervention variables. In general, these studies have produced contradictory findings. An integrated Bayesian forecasting and dynamic modeling approach used to determine the impact of the increased speed limit on rural Interstates of Iowa is reported. The approach is used to verify that raising the speed limit to 65 mph (104.6 km/h) led to an increase in fatal accidents on rural Interstates of Iowa. Comparison of fatal accident data on rural Interstates of Iowa and New Jersey yields similar results. Although this conclusion was anticipated, the study further demonstrates that a Bayesian/dynamic approach is more robust than the standard time series model.

scholarly journals Effects of Speed Limit Enforcement Cameras on Accident Rates

2003 ◽  
Vol 1830 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Stephane Hess ◽  
John Polak
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
Series Data ◽  
Speed Limit ◽  
Regression To The Mean ◽  
Average Decrease ◽  
The Best Approximation ◽  
Before And After ◽  
Accident Data ◽  
Accident Rates

Speed limit enforcement cameras (SLECs) have been in operation in Great Britain since 1991. However, there is still considerable dispute regarding their effectiveness in reducing accident rates. The aim of this research was to analyze the effects of SLECs on accident rates in Cambridgeshire, United Kingdom, using time series data collected over an 11-year period. A time series analysis of the accident data revealed the presence of both trend and seasonality components. A method was developed to remove the influence of these two components from the data and compare mean accident levels before and after installation of the camera. The method was also constructed in such a way that it would be able to distinguish between the actual effects of the camera installation and the effects of regression to the mean. The initial investigation into the effects of SLECs showed an average decrease over sites in the monthly accident frequency by around 18%; a more detailed analysis suggested that the best approximation of the effect of the introduction of a SLEC is a decrease in injury accidents by 31.26%, thus giving clear evidence that SLECs do indeed contribute to a significant decrease in accident numbers.

scholarly journals Changes in the Use of Broad-Spectrum Antibiotics after Cefepime Shortage: a Time Series Analysis

2011 ◽  
Vol 56 (2) ◽  
pp. 989-994 ◽  
Author(s):  
C. Plüss-Suard ◽  
A. Pannatier ◽  
C. Ruffieux ◽  
A. Kronenberg ◽  
K. Mühlemann ◽  
...  
Keyword(s):  
Time Series ◽  
Pseudomonas Aeruginosa ◽  
Broad Spectrum ◽  
Interrupted Time Series ◽  
Antibiotic Policy ◽  
Content Type ◽  
Broad Spectrum Antibiotics ◽  
Before And After ◽  
Alternative Antibiotic ◽  
The Impact

ABSTRACTThe original cefepime product was withdrawn from the Swiss market in January 2007 and replaced by a generic 10 months later. The goals of the study were to assess the impact of this cefepime shortage on the use and costs of alternative broad-spectrum antibiotics, on antibiotic policy, and on resistance ofPseudomonas aeruginosatoward carbapenems, ceftazidime, and piperacillin-tazobactam. A generalized regression-based interrupted time series model assessed how much the shortage changed the monthly use and costs of cefepime and of selected alternative broad-spectrum antibiotics (ceftazidime, imipenem-cilastatin, meropenem, piperacillin-tazobactam) in 15 Swiss acute care hospitals from January 2005 to December 2008. Resistance ofP. aeruginosawas compared before and after the cefepime shortage. There was a statistically significant increase in the consumption of piperacillin-tazobactam in hospitals with definitive interruption of cefepime supply and of meropenem in hospitals with transient interruption of cefepime supply. Consumption of each alternative antibiotic tended to increase during the cefepime shortage and to decrease when the cefepime generic was released. These shifts were associated with significantly higher overall costs. There was no significant change in hospitals with uninterrupted cefepime supply. The alternative antibiotics for which an increase in consumption showed the strongest association with a progression of resistance were the carbapenems. The use of alternative antibiotics after cefepime withdrawal was associated with a significant increase in piperacillin-tazobactam and meropenem use and in overall costs and with a decrease in susceptibility ofP. aeruginosain hospitals. This warrants caution with regard to shortages and withdrawals of antibiotics.

A Topic Modeling Approach to Study the Impact of Manager Interventions on Design Team Cognition

2020 ◽  
Author(s):  
Joshua T. Gyory ◽  
Kenneth Kotovsky ◽  
Jonathan Cagan
Keyword(s):  
Problem Solving ◽  
Topic Modeling ◽  
Process Management ◽  
Topic Model ◽  
Design Team ◽  
Design Cognition ◽  
Team Cognition ◽  
Modeling Approach ◽  
Before And After ◽  
The Impact

Abstract In order to computationally study design cognition under design process management, this work utilizes a topic modeling approach to analyze design team discourse during problem-solving. The particular experimental design, from previous work by the authors, places one of the design team conditions under the guidance of a human process manager. In that work, teams under this guidance outperformed the unmanaged teams in terms of their design solutions. This opens the opportunity to not only model design discourse during problem solving, but also explore the impact of process manager interventions and their impact on design cognition. Utilizing this approach, a topic model is trained on discourse of human designers, for both managed and unmanaged teams, collaboratively solving a design problem. Results show that the two team conditions significantly differ in a number of the extracted topics, and in particular, those topics that most pertain to the manager interventions. Furthermore, a before and after analysis of the topic-motivated interventions, reveals that the process manager interventions significantly shift the topic mixture of the team members’ discourse toward that of the interventions immediately after they are provided. Together, these results not only corroborate the effect of the process manager interventions on design team discourse and cognition, but provide promise in the computational detection and facilitation of design interventions based on real-time discourse data.

The effect of lodging tax increases on US destinations

2019 ◽  
pp. 135481661989075 ◽  
Author(s):  
Simon Hudson ◽  
Fang Meng ◽  
Kevin Kam Fung So ◽  
Scott Smith ◽  
Jing Li ◽  
...  
Keyword(s):  
Time Series ◽  
Economic Loss ◽  
The United States ◽  
Tax Rates ◽  
Daily Rate ◽  
States Data ◽  
Before And After ◽  
The Impact ◽  
The City ◽  
Room Time

This study examined the impact of lodging tax increases on eight different destinations of the United States. Data were collected via in-depth stakeholder interviews and monthly statistics provided by Smith Travel Research including average daily rate, occupancy, and revenue per available room. Time series analysis was employed to estimate the impact of tax increases in each destination by analyzing that time series before and after the imposition of the tax. Overall, our results did not fully support the hypothesis that when a city’s hotel tax greatly increases above that of an easily accessible competitor, it will result in an economic loss to the city with the disproportionate tax rates. Hotels appear to have absorbed any tax increases with little impact to their businesses, but there was concern among stakeholders as to how the lodging tax was spent.

scholarly journals Assessing the impact of retraction on the citation of randomized controlled trial reports: an interrupted time-series analysis

2018 ◽  
Vol 24 (1) ◽  
pp. 44-51 ◽  
Author(s):  
Andrew Mott ◽  
Caroline Fairhurst ◽  
David Torgerson
Keyword(s):  
Time Series ◽  
Randomized Controlled Trial ◽  
Randomized Controlled Trials ◽  
Controlled Trial ◽  
Interrupted Time Series ◽  
Controlled Trials ◽  
Interrupted Time Series Analysis ◽  
Randomized Controlled ◽  
Before And After ◽  
The Impact

Objectives To assess the impact of retraction on the citation of randomized controlled trials. Methods We used an interrupted time-series with matched controls. PubMed, CINHAL, Google and the Retraction Watch Database were searched. We identified retracted publications reporting the results of randomized controlled trials involving human participants with two years of available data before and after retraction. We obtained monthly citation counts across all articles for the 24 months before and after retraction, from Web of Science. We used a Poisson segmented regression to detect changes in the level and trend of citation following retraction. We also undertook a matched control analysis of unretracted randomized controlled trials and a sensitivity analysis to account for cases of large-scale, well-advertised fraud. Results We identified 387 retracted randomized controlled trial reports, of which 218 (56.3%) were included in the interrupted time-series analysis. A reduction of 22.9% (95% CI 4.0% to 38.2%, p = 0.02) was observed in the number of citations in the month after retraction, and a further reduction of 1.9% (95% CI 0.4% to 3.5%, p = 0.02) per month in the following 24 months, relative to the expected trend. There was no evidence of a statistically significant reduction among the matched controls. Authors with a large number of retractions saw a 48.2% reduction at the time of retraction (95% CI 17.7% to 67.3%, p = 0.01). Other cases had a more gradual reduction with no change at the time of retraction and a 1.8% reduction per month in the following 24 months (95% CI 0.2% to 3.4%, p = 0.03). Conclusions Retractions of randomized controlled trial reports can be effective in reducing citations. Other factors, such as the scale of the retractions and media attention, may play a role in the effectiveness of the reduction.

Evaluation of Speed Limits in Kentucky

1998 ◽  
Vol 1640 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Kenneth R. Agent ◽  
Jerry G. Pigman ◽  
Joel M. Weber
Keyword(s):  
Speed Limit ◽  
Review Of Literature ◽  
Speed Limits ◽  
Fatal Accident ◽  
Engineering Study ◽  
Before And After ◽  
Accident Data ◽  
Accident Rates ◽  
Specific Section ◽  
Moving Speed

The objectives were to examine current criteria and procedures used for setting speed limits and to determine appropriate speed limits for various types of roads. The study involved a review of literature, collection and analysis of speed data, and collection and analysis of accident data. The speed data included moving speed data on various highway types and a comparison of speed data before and after speed limit changes. Accident data were collected at locations where speed limits were changed and also on sections of adjacent Interstates with different speed limits. The speed data indicate that a large percentage of vehicle speeds exceed posted speed limits, with the highest percentage being on urban Interstates and two-lane parkways. The speeds for trucks were slightly lower than for cars. A comparison of speed data at locations where speed limits were changed showed only slight differences. A comparison of accident rates at adjacent sections of Interstate where the speed limit was 88.6 km/hr (55 mph) and 104.7 km/hr (65 mph) did not find a substantial difference in the total, injury, or fatal accident rates. Except where legislatively mandated speed limits apply, the 85th-percentile speed should be used to establish speed limits. Maximum limits are given for various types of roadways. Different speed limits for cars and trucks are recommended for some roadways. An engineering study must be conducted before the speed limit should be changed for any specific section of roadway.

The 55 Miles Per Hour Maximum Speed Limit

PEDIATRICS ◽  
1991 ◽  
Vol 88 (3) ◽  
pp. 654-654
Author(s):  
Keyword(s):  
Maximum Speed ◽  
Speed Limit ◽  
Mortality And Morbidity ◽  
Interstate Highways ◽  
High Speeds ◽  
Surface Transportation ◽  
Relocation Assistance ◽  
Relationship Of ◽  
The Relationship ◽  
Act One

The first significant reduction in three decades in the number of highway deaths was noted in this country when the 55 miles per hour (mph) national speed limit became law in 1973. Where this speed limit is still in force, the reduction in automobile deaths and injuries has been maintained. In 1987, however, Congress passed the Surface Transportation and Uniform Relocation Assistance Act. One of the provisions of this act was to allow states to raise the speed limit on most rural interstate highways to 65 mph. Because the average highway speed routinely exceeds the prevailing legal limit by at least several miles per hour, the higher speed limit has markedly increased the proportion of traffic traveling at very high speeds. In 1988, 3 times as many vehicles were exceeding 70 mph and 11 times as many vehicles were traveling at speeds greater than 80 mph as in 1986 when the 55 mph speed limit prevailed. These higher speeds have been accompanied by appreciable increases in automobile crash deaths and injuries. The relationship of automobile mortality and morbidity to the speed limit is well documented. The American Academy of Pediatrics endorses a return to the national maximum speed limit of 55 mph as an effective method of lowering the incidence of automobile deaths and injuries. Pediatricians should make every effort to support this form of injury prevention by personal example, education of pediatric patients and their parents, and legislative advocacy.

Correlation between tropical-like cyclones in the Mediterranean Sea and the space weather

2020 ◽  
Author(s):  
Medžida Mulić ◽  
Džana Halilović ◽  
Anesa Lavić
Keyword(s):  
Time Series ◽  
Mediterranean Sea ◽  
Tropical Cyclones ◽  
Space Weather ◽  
Electron Content ◽  
Before And After ◽  
The Mediterranean ◽  
Tec Variability ◽  
The Tropics ◽  
The Impact

<p>The ionosphere is the dominant source of the errors in the Global Navigation Satellite Systems  (GNSS), which causes delays and degradation of the GNSS signal. These errors have an impact on many terrestrial and space applications that rely on GNSS. The key parameter for the study of the ionosphere is the Total Electron Content (TEC). In an effort to eliminate the impact of delayed GNSS signal caused by the ionospheric refraction on the accuracy of GNSS positioning and navigation, the researchers made significant advances and began other ionospheric research. This paper studies the variability of GNSS derived TEC values in the International quiet and disturbed days, but also in periods when three tropical-like cyclones in the Mediterranean developed. However, the term tropical-like cyclone distinguishes tropical cyclones developing outside the tropics (like in the Mediterranean Basin) from those developing inside the tropics. Mediterranean tropical cyclones, known as a Medicane, show no difference to other tropical cyclones and can be developed into a hurricane.</p><p>Hence, the variability of GNSS derived TEC values time series were analyzed during periods when three Medicanes happened in the fall of 2014, 2016, 2017. Data from eight GNSS stations of the European Permanent Network (EPN) were used and TEC calculations were performed using the VShell program. The results demonstrated that the TEC variability is reflected in daily variations within one month, for three different years of consideration. When the state of the ionosphere was disturbed by external influences, such as the space weather storms, the results demonstrated extreme changes in the number of electrons in the ionosphere. Variations of the TEC and parameter VTEC*sigma were analyzed in the weeks before and after three subtropical cyclones in the Mediterranean Sea, recorded in November 2014, November 2016 and November 2017. Special attention was given to the time series analysis of the variable VTEC*sigma for the GNSS stations located nearby the area where the Medicane developed and stations in regions away from the storm.</p><p>The results demonstrated higher VTEC values derived from GNSS stations in the area of the storm on the storm days, as well as the days before and after. Also, the results for the storm in November 2014 showed higher VTEC values compared to the other two tropical-like cyclones. The recorded events of space weather are in correlation with the days when three analyzed Medicanes developed. Therefore, it is difficult to distinguish whether the TEC variability was caused by the space weather storm or the Medicane.</p>

scholarly journals Analysis of COVID-19 pandemic trends and its impact on the health system of the main urban centers of Minas Gerais, Brazil.

2020 ◽  
Vol 8 (11) ◽  
pp. 621-633
Author(s):  
Larissa Pereira Caixeta ◽  
Tathiane Ribeiro da Silva ◽  
Douglas Eulálio Antunes
Keyword(s):  
Time Series ◽  
Health Systems ◽  
Kendall Test ◽  
Minas Gerais ◽  
Urban Centers ◽  
Social Distancing ◽  
Epidemic Curve ◽  
Before And After ◽  
Belo Horizonte ◽  
The Impact

Objectives: In this study, related to COVID-19, we characterized the epidemiologic, trends and the impact of new coronavirus on the health systems of the main urban centers in Minas Gerais, Brazil. Methods: A retrospective time series encompassing data associated with COVID-19 disease, from March to July of 2020, were approached for verifying the trends of social distancing rate and number of daily deaths by means of Mann-Kendall test. The Binomial test was performed to analyzing the differences between percentages of two periods (before and after pandemic) with the goal to measure the impact of disease on health systems. Results: Although the social distancing rates for the main urban centers of Minas Gerais presented declining trend along the time series, Juiz de Fora had the best rate and, consequently, flattened the epidemic curve for new cases of the disease, besides of to notify the lowest number of deaths (Mann-Kendall [Belo Horizonte]: -0.77, p<0.001; Mann-Kendall [Juiz de Fora]: -0.74, p<0.001; Mann-Kendall [Uberlandia]: 0.29, p<0.001). The number of oncologic treatments in Belo Horizonte (April 2019 vs April 2020= -41.5%; p<0.001) and clinical treatments in Uberlandia (March 2019 vs March 2020= -51.7%; p<0.0001) have reduced drastically before and after pandemic. Conclusions: Therefore, the implementation of a higher social distancing rate could flatten the epidemic curve avoiding an increase in deaths number and to reduce the impact of COVID-19 on health systems preventing the collapse of them.

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