Thursday - Survival analysis
17 important questions on Thursday - Survival analysis
What is survival analysis about?
Not only if, but also when event takes place is relevant
What are time-to-event variables?
What are examples of survival data?
Epidemiology - age at certain infection, time from HIV to AIDS
Demography - time to death or time to birth of first child
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What is typical for survival studies?
What happens when data is collected in a survival study?
What is censoring (in survival studies)?
--> most relevant is right censoring, event took place at the right of the end of observation
Which method is used in survival analysis?
How do you make calculations with the kaplan-meier method?
Where we use the p for time points where the number of people in the study changes.
p = 1 - d/r (1-hazard)
--> d is number of events and r is number of people at risk
How does a typical Kaplan-Meier table looks like?
Nr of death
Nr under observation (also censored subtracted!)
Death hazard
Survival hazard
Survival probability
What is important when estimating the median for survival analysis?
What is the difference between a local and global test in survival analysis?
Global = compares two or more time points over whole time range (compare curves) and test whether S(A) = S(B) for all time points
Which test is used in survival analysis for a global test?
When is it not smart to use a log-rank test?
How it the hazard ratio calculated?
-> h1 and h2 are hazard rates
-> we assume that HR is a constant
What is the relation between survival function and hazard ratio?
H = H0*exp(ß1*x + ß2*x etc)
What are differences between KM plot and curve based on cox model?
--> curves look highly similar
What to do when you have non-proportional data? (instead of cox model)
- different model (complex)
- stratification
- artificial censoring
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