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Hi, Can anybody tell me what the message below means and how to overcome it. Thanks, Neil Warning message: X matrix deemed to be singular; variable 2 in: coxph(Surv(age_at_death, death) ~ project$pluralgp + project$yrborn + ......... >

Dear R users, In order to illustrate the possible effects of events on variables plotted against time, I would like plot a time line of events along side the plot of the variables. The x-axis should be some time unit; the y-axis should be the variable of interest; the time line should be plotted below the graph along the same x-axis scale. As I have many variables and different events