Prognostic factors identified from phase I and II studiesBased on preliminary evidence, older age may be associated with poorer disability recovery. Development and Internal Validation: the Saskatchewan datasetWe developed the model using data from a population-based, inception cohort of traffic injury from Saskatchewan [18]. Replicating: repeating the Models in the Ontario datasetWe replicated our models using data from a randomized clinical trial that investigated the effectiveness of physiotherapy and physician-based care for the management of NAD [19]. We determined the predictive ability of each model using Harrell’s concordance C-statistic [3]. Internal validation of the Prediction ModelWe tested the internal validity of our predictive models using bootstrapping [3].