R help - Jul 2005 - fitting Weibull distribution on observed percentiles

Hi , R Users

I'm trying to fit a Weibull ditribution on observed percentiles using nls
but it doesn't work. Here is the code I use: is there something wrong ?

# p corresponds to percentiles
# and q to the observed values
# the datas are from the livebirth in france in 1998 distribution

ined1998   <- data.frame(   p = c(0.01638,0.49629,0.99284) , 
                                       q = c( 18,27,41))

a0<- 3 
b0<- ined1998$q[2]/gamma(1+1/a0)

dist_w1998 <- nls(ined1998$q ~ qweibull(ined1998$p , a0 ,                    
b0) , start = c(a0,b0) , data=ined1998)

I look forward your reply


C.M
URC NECKER 




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