Lets suppose I have aggregate survival probabilities (NOT individual level data) from Kaplan Meier curves. I would like to curve fit different "types" of distribution like exponential, weibull, log-normal, and log-logistic on this curve so that I can extrapolate.
Below is the sample data derived from KM for aggregated data.
surv <- c(0.92,0.86,0.80,0.77,0.73,0.70,0.68,0.63,0.61,0.59,0.57)
Below are my questions:
- How would I curve fit the data to the aforementioned distributions, to derive parameters such as scale and shape in case of weibull?
- Any illustrative examples in
Rwould very helpful.