Hi!

I have following data which is left truncated say at 10. I am trying to estimate the parameters of the Truncated Lognormal distribution to this data as given below. 

(I have referred to R code appearing in an earlier post - http://finzi.psych.upenn.edu/Rhelp10/2008-October/176136.html)

library(MASS)

x <- c(600.62,153.05,70.26,530.42,3440.29,97.45,174.51,168.47, 116.63,36.51, 219.77, 231.67,110.62,173.11,202.85,689.27,23.82,234.15,625.89,192.88,29.53,109.99, 80.53, 46.85,82.69,231.53,75.38,217.52,85.29,182.18)

ltlnorm <- function(x, meanlog, sdlog, log=FALSE)

{
dlnorm(x, meanlog, sdlog, log = FALSE) / plnorm(1, meanlog, sdlog, lower.tail = TRUE, log.p = FALSE)
}

meanlog = mean(log(x))
sdlog = sd(log(x))

ltlnormfit <- fitdistr(x,ltlnorm, start=list(meanlog,sdlog))


I get following error - 

Error in dlnorm(x, meanlog, sdlog, log = FALSE) : element 3 is empty;
   the part of the args list of '.Internal' being evaluated was:
   (x, meanlog, sdlog, log)


Please guide me as to 

(1) How do I overcome this error;

(2) In the function, I have defined plnorm(1, meanlog, sdlog, lower.tail = TRUE, log.p = FALSE). The usual syntax is  plnorm(q, meanlog = some value,  sdlog = some value, lower.tail = TRUE, log.p = FALSE). I have taken q as 1. Should it be the truncation point i.e. 10. and lastly

(3) I have defined meanlog and sdlog  as mean(log(x)) and sd(log(x)) respectively. Am I write in doing so?

Please guide me. I have used this fitdistr for the first time.

Regards

Julia 






************************************************



Only a man of Worth sees Worth in other men



************************************************


      
	[[alternative HTML version deleted]]

