Dear R/Statistics-gurus! I tried to find answer to my hypothetical question and in vain. Sorry, I don't have a dataset that fits into this hypothetical question and pardon me if my explanations/use of statistical terms are not accurate.
It does sound a weird question, but I want to rule out that line of thought. Is it possible to develop a model (or a simulation) such that the upper variability is different from lower variability? e.g, the upper variability in the data above a model predicted value may be less than the variability in the data below a model predicted value. I guess mixture model is not applicable here Around a population estimate (say, mean or maximum likelihood) one of the following may apply: total standard deviation (SD) = SD(lower) + SD(upper) total variance (var) = var(lower) + var(upper); If it is possible, how do I assign variability in parameters and residual (additive + proportional) errors? To fit the observed, Y = F + (a^2 +b^2/F^2) F = f(x,Ai, var(Ai)); where Ai = a matrix of parameters; x = a vector independent variables; var(Ai) = variability in the parameter (Ai) Regards, Santosh [[alternative HTML version deleted]] ______________________________________________ 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.