Prediction of Injury and Fatality Probability

Univariate logistic regression was performed with respect to the explanatory variables, in part as a first step to determine which variables to enter into multivariate analysis and secondly to explore which variables are predictors of the dependent variables. As quite many factors become significant (p-value 0.05) in univariate analysis, only models for ISS and for fatalities are presented and discussed here. 

The odds ratios in the tables presented below refer to an additional risk associated with a significant odds ratio 1 (or decrease associated with an odds ratio 1). 

Age of the pedestrian (jped) is associated with a higher risk (unadjusted odds ratios between 1.863 and 2.489) [19-21], BMI is also associated with an increase in risk (unadjusted odds ratios between 1.467 and 1.835). 

Interpretation of the effects evoked by the explanatory variables on injury or mortality involves hypotheses about injury causation as well as the expected trend. Since impact speed is a dominant determinant for injury and fatality, any explanatory variable that is associated with impact speed could act as a surrogate for impact speed and thus as a confounder, i.e., be significant without having a causal relationship or mask the original effect size due to the association with impact speed. Potential associations were tested using Pearson and Spearman correlations for continuous variables and t-tests and Mann-Whitney-Tests for non-continuous (binary) variables. P-values refer to the hypotheses of a correlation (for continuous variables) or to differences between the two groups (for binary variables). 

Variable Symbol N nlSS Scaling p-value Unadjusted 95 % Cl AlC BIC 

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Prediction of Injury and Fatality Probability 53. 3 Multivariate Models Based on PCDS... 

There are a few models in the literature which are based on GIDAS and predict the probability for a particular injury level or for fatalities. The coefficients of the models are not directly comparable, as each model uses a different data set and probably a different scaling for the explanatory factors. The first two models for MAIS2+ and MAIS5+ are based on impact speed. They are not included explicitly in the publication, but only given as diagram [4]. 

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