1,720,990 research outputs found
Estimating the effect of proximity to school on cyclist safety using a simultaneous-equations model with heterogeneity in covariance to address potential endogeneity
No full textTraffic safety around schools is a major concern for policy makers and as such safety interventions are often targeted near schools. This paper shows the importance of accounting for the potential endogeneity of proximity to school when attempting to estimate its impact on traffic safety. In this research, we use a Bayesian simultaneous econometric approach with heterogeneity in covariance to disentangle the true effect of proximity to school on cyclist injury frequencies at signalised intersections in an urban setting. We assess the robustness of the bivariate normal assumption, using a scale mixing approach. Notably, we found that proximity to school was associated with an increase in cyclist injuries and this association was stronger when endogeneity was accounted for in the model, confirming the importance of considering endogeneity in studies of traffic safety near schools. Our heterogeneity in covariance specification revealed systematic variations in the covariance structure, which would otherwise go unobserved, providing further insights into sources of heterogeneity with the same set of variables available in the data. A safety-in-numbers effect is also found for cyclists in the study area and period. This research offers policy implications based on the findings of the analysis including the need for safety interventions at intersections with high vehicle turning counts and those in proximity to public transport stops, and better informing decision-makers regarding the magnitude of the impact of proximity to school on cyclist safety at intersections.<br/
Analysing the macro-level determinants of traffic safety for pedestrians and cyclists in England
No full textWalking and cycling are often seen as ways to contribute to the future of greener, less congested, more active transport. It is common for governments to encourage people to walk or ride their journeys rather than using motor vehicles, however crash rates per kilometre travelled are notably higher for pedestrians and cyclists than cars or similar modes of travel. Bike sharing schemes in particular are a relatively new concept in the world of transport and are often hailed by policy makers as an efficient way to travel and yet the safety effects of their use is thus far under-researched compared to other modes.This research conducted a macroscopic investigation to identify area-level factors which have a significant association with active travel crashes. The data used concerns England and Greater London with crashes in the period 2018-2019 as well as the post-COVID period of 2022. The principal method of analysis is a Bayesian approach capable of addressing a number of statistical issues. The complexity of the models involves accounting for the following: the endogeneity of a bike share scheme’s presence on crash frequency to more accurately identify the true impact of the presence of these schemes on safety; unobserved heterogeneity which biases parameter estimates; and the temporal instability of explanatory factors which can mean they affect safety differently across different time periods.A number of factors were significant across the models such as those related to deprivation, including crime and unemployment, being associated with a higher crash frequency. Also, most models showed a safety in numbers effect where an increase in the number of pedestrians or cyclists was associated with an increase in crashes that was smaller than would be expected if the two were proportional. This indicates that more road users means greater individual safety. For the majority of the modelled variables, the direction of the association (i.e., increase or decrease of crashes) was consistent across England and Greater London suggesting that these findings might be applicable to other cities. The crash frequencies of active travellers before and after the COVID period was found to be significantly different, but the association with bike share presence appeared to be temporally stable.Bike sharing schemes on the other hand appear to have a complex association with crashes. In Greater London, bike share presence generally appeared to be associated with a reduction in safety, but this was not the case once endogeneity was accounted for; whereas across the rest of England the opposite was mostly found. This would seem to suggest that in Greater London bike share schemes are introduced in inherently ‘unsafe’ locations i.e., those where crash frequency is relatively higher generally due to area characteristics, but in other parts of England they are introduced in those areas which are inherently ‘safe’. The effect of the bicycle share schemes themselves on safety remains ambiguous.Overall, this research builds a better understanding of active travel safety by providing more robust analysis which addresses endogeneity and unobserved heterogeneity. Policy recommendations can also be given such as a need to target safety interventions in more deprived areas for maximum effectiveness, as well as the importance of practitioners considering the confounding effect of safety infrastructure
Examining the impact of exposure, built environment and socio-demographics on pedestrian safety: A case study of Greater London
No full textWalking as a mode of travel alleviates congestion, pollution and concerns over physical fitness. However, safety concerns might be a barrier for some people to walking more often, so finding ways to improve pedestrian safety is important. This paper conducts a ward-level study of Greater London such that factors which are associated with pedestrian safety can be identified and interventions to improve safety can be more appropriately targeted. A wide range of factors relating to exposure, land use, built and natural environment, and socio-demographics, including markers of deprivation were considered in our analysis. We employed a multilevel random parameters negative binomial regression model with a hierarchical structure which encompassed the boroughs and wards of Greater London allowing dependency in the data and unobserved heterogeneity to be addressed more fully. The results show that BAME population, number of schools, job density and alcohol expenditure are associated with an increase in pedestrian crashes as are crime rate and children in child benefit households, which are both markers of deprivation. Also, the average number of cars per household, the proportion of green space and the percentage of adults who commute by walking have a decreasing effect on pedestrian crash frequency. This study identifies important determinates of ward-level pedestrian safety and estimates the magnitude of their association with pedestrian safety and in doing so reveals important between borough (local authority) differences in the Greater London area in terms of pedestrian safety which were not previously known or well-understood.</p
Investigating the association between neighbourhood characteristics and e-scooter safety
No full textThe uptake of e-scooters as an alternative mode of travel has risen sharply in recent years; however, their safety is less-understood compared to other modes of travel. For the first time in the extant literature, we explore the association between neighbourhood characteristics and e-scooter safety in Greater London, UK. We found that, over the study period, the expected e-scooter crash frequency was the highest in the City of London, followed by the West End, and then St. James's―both wards located in the borough of Westminster in central London. We found that e-scooter crash frequencies increase with an increase in area-level walking and cycling activities. Similarly, we found that the number of schools is positively associated with the expected e-scooter crash frequency. In contrast, the results indicated that as the proportion of ward-level greenspace increases, the number of crashes involving e-scooters decreases. The results also highlighted social inequalities in this context, with higher e-scooter crash frequencies in areas with larger Black, Asian and Minority Ethnic population, those with higher crime rates, and those with a higher population of children in out of work households. This research provides practical recommendations to prioritise areas for safety interventions and for selecting suitable safety improvement programmes.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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