On Aug 30, 2015, at 8:41 AM, Shant Ch via R-help wrote: > Thank you very much to all for all your responses. > > @Dr. Winsemius, E[f(X)] >=f(E(X)) if f is convex. Now we know |x| is convex > function, so clearly in this scenario if we compute the expectation of the > ((X1+X2+X3)/3-X4) and then take the absolute, then, we will get a lower bound > of the expectation I want to find. >
I understood the error in my thinking when Jeff Newmiller pointed out the minus sign that I had missed. Thanks; David. > On Saturday, August 29, 2015 7:24 PM, David Winsemius > <dwinsem...@comcast.net> wrote: > > > > On Aug 29, 2015, at 11:35 AM, Shant Ch via R-help wrote: > >> Hello Dr. Berry, >> >> I know the theoretical side but note we are not talking about expectation of >> sums rather expectation of ABSOLUTE value of the function >> (X1/3+X2/3+X3/3-X4), i.e. E|X1/3+X2/3+X3/3-X4| , I don't think this can be >> handled for log normal distribution by integrals by hand. >> > > To Shnant Ch; > > I admit to puzzlement (being a humble country doctor). Can you explain why > there should be a difference between the absolute value of an expectation for > a sum of values from a function, in this case dlnorm, that is positive > definite versus an expectation simply of the sum of such values? > > -- > > David Winsemius > Alameda, CA, USA > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
