Hi there. I am working on gene expression data of a pan-cancer project. I am new in survival analysis and have a question about coxph function in R package "survival". I have z-score of my gene expression levels which contains negative and positive values. the question is ,can I use this data with negative values to perform univariate cox regression analysis? what about multivariate cox regression analysis? Thanks.

Yes. I have seen your comment very useful. So thanks to you, I am now sure about my path in analysis. Thanks so much