Question

What are the assumptions of survival analysis?

What are the assumptions of cox fit hazard ratio?

Are these assumptions the same thing?

Answer 1

For survival analysis, there are three assumptions:

• Subjects that are censored have the same survival prospects as those who continue to be followed.
• Survival probability is the same all the subjects, irrespective of when they are recruited in the study.
• The event of interest happens at the specified time. This is because the event can happen between two examinations. The estimated survival time can be more accurately measured if the examination happens frequently i.e if the time gap between examinations is very small.

There are three assumptions made by the Cox Model:

• The Hazard Ratio of two subjects remains the same at all times.
• The Explanatory Variables act multiplicatively on the Hazard Function.
• Failure times of individual subjects are independent of each other.