Dear Sir/Madam, As mentioned in help, R reports error while fitting Johnson distribution by method of moments. I have used moments from Weibull distribution and hence it is well within the feasible area and try to fit Johnson distribution using method of moments.
As for example, shape=0.5 # Shape Parameter of IID Weibull Stress # scale=1 # Scale Parameter of IID Weibull Stress # # kth order raw moment of Weibull # k_raw= function(k) (scale^k)*(gamma(1+k/shape)) # Cumulants # k1=k_raw(1) k2=k_raw(2)-(k_raw(1))^2 k3=k_raw(3)-3*k_raw(2)*k_raw(1)+3*(k_raw(1))^3 -(k_raw(1))^3 k4=k_raw(4)-4*k3*k1-3*(k2)^2 - 6*(k2)*(k1)^2-(k1)^4 # Central Moments # theta=c( k1, k2 , k3 , k4+3*(k2)^2) parms<-JohnsonFit(theta,moment="use") Error in JohnsonFit(theta, moment = "use") : Couldn't do an Sb fit I will be thankful if you please let me know elaborately the exact difficulty which causes such errors. Regards, Prajamitra Bhuyan ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
