SPSS Survival analysis - Should I split data file by groups or use covariates instead


New Member
Hello! I have to assess different factors affecting the survival after transplantation. Can you advise me which is better (or more correct)?
- to split the data file by groups (for example type of disease - malignant or non-malignant) and analyze the effect of other factor/s (e.g. HLA compatibility, donor type - related or unrelated and etc.);
- or I should not split it, but use Cox regression instead and add those factors as covariates? In that case how should I interpret the results and more specifically - its significance and the independent role of each factor?
Thank you very much for your help!