[R] fitting the gamma cumulative distribution function

[Tim Bergsma]

Hi.

I have a vector of quantiles and a vector of probabilites that, when 
plotted, look very like the gamma cumulative distribution function.  I 
can guess some shape and scale parameters that give a similar result, 
but I'd rather let the parameters be estimated.  Is there a direct way 
to do this in R?

Thanks,

Tim.

week <- c(0,5,6,7,9,11,14,19,39)
fraction <- c(0,0.23279,0.41093,0.58198,0.77935,0.88057,0.94231,0.98583,1)
weeks <- 1:160/4
plot(weeks, pgamma(weeks,shape=6,scale=1.15),type="l")
points(week,fraction,col="red")