Epidemiology of child pedestrian casualty rates: Can we assume spatial independence?
Section snippets
Background
There is a plentiful literature modelling child pedestrian casualty rates, in particular these demonstrate a strong association with areal socio-economic status (Kendrick, 1993, Jolly et al., 1993, Braddock et al., 1991, Roberts et al., 1992, Chichester et al., 1998, Lyons et al., 2003) Recently, a study released in the UK by the Institute of Public Policy Research (IPPR) offered an econometric analysis of child pedestrian casualty rates (Grayling et al., 2002) and claimed there was little
Methods
For the purposes of this study a child is defined as being in the age range 0–15 years.
Diagnostic tests for spatial dependence
There are conceptual reasons for believing that there may be lack of independence in terms of the casualty home location rather than the collision location (MacNab, 2004). For example, if there are indeed casualty related covariates influencing risk, these would tend to be taken with the casualty to other locations. One initial investigative measure for spatial independence is the Geary C statistic (Cliff and Ord, 1981) Results are given in Table 4 which suggest a value of 1.0272 for the
Discussion
There have been attempts recently using multilevel modelling in order to attempt to disentangle areal effects from individual effects (Reading et al., 1999, Haynes et al., 2003, Jones and Jorgensen, 2003) which would go a long way toward addressing ecological concerns surrounding this kind of analysis. However, the situation remaining is clearly one where there is considerable confounding and interaction between individual and environmental factors. It would be therefore most interesting to
Conclusions
Ecological analyses are popular largely because the data are widely available, there are both cost and confidentiality reasons which limit the amount of research conducted at an individual level and are likely to continue to provide part of the body of evidence used to guide interventions. Firstly it needs to be noted that the underlying data are based entirely on an administrative abstraction of an observed phenomenon. Secondly, it is important that methodological developments underpinning
References (38)
- et al.
An investigation into the relationships between area social characteristics and road accident casualties
Accid. Anal. Prev.
(1997) - et al.
Road accident statistics – a comparison of police and hospital information
Accid. Anal. Prev.
(1973) Possible aggregation biases in road safety research and a mechanism approach to accident modeling
Accid. Anal. Prev.
(2004)- et al.
The effects of area deprivation on the incidence of child and adult pedestrian casualties in england
Accid. Anal. Prev.
(2005) - et al.
Household and neighbourhood risks for injury to 5–14-year-old children
Soc. Sci. Med.
(2003) - et al.
The use of multilevel models for the prediction of road accident outcomes
Accid. Anal. Prev.
(2003) - et al.
An ecological study of the locations of schools and child pedestrian injury collisions
Accid. Anal. Prev.
(2004) A Bayesian hierarchical model for accident and injury surveillance
Accid. Anal. Prev.
(2003)Bayesian spatial and ecological models for small-area accident and injury analysis
Accid. Anal. Prev.
(2004)- et al.
The severity of pedestrian injuries in children: an analysis of the Pedestrian Injury Causation Study
Accid. Anal. Prev.
(1990)