I'm using the FIREBROWSE platform and I'm trying to replicate the survival analysis described here:
In the description of the method used they reported: " logrank test in univariate Cox regression analysis with proportional hazards model was used to estimate the P values comparing quantile intervals using the 'coxph' function in R. Kaplan-Meier survival curves were plotted using quantile intervals at c(0, 0.25, 0.50, 0.75, 1). If there is only one interval group, it will not try survival analysis."
This description is not really clear to me. I know that I can estimate the logrank p-value using the coxph function, but I can't understand how they used the quantile intervals information.
Sorry if the question is trivial and thanks for your help.