Time-to-Event Analysis for Onset of Neurological Symptoms and for Survival Duration.1, 2

1Testing Terms: In Kaplan-Meier analysis the Log-Rank test places more weight on later event times; the Wilcoxon test places more weight on early event times and is the optimum rank test if the error distribution is logistic. Prob>ChiSq lists the probability of obtaining, by chance alone, a Chi-square value greater than the one computed if the time-to-event functions are the same for all groups. In Cox proportional hazards analysis a Risk Ratio of 1.00 occurs when timing is likely identical in the two groups. The Effect Likelihood Test is the likelihood-ratio Chi-square test on the null hypothesis that the parameter estimate for the Treatment covariate is zero (no effect of treatment). Testing term descriptions are taken from the JMP? 7.0.1 Help file.2A neurological score of two in both hind limbs is taken to be the definitive onset of neurological symptoms.