Hi, Your question is puzzling. First, you should clarify what you mean by zero inflated distribution. Second, a normal score transform should by construction always yield a set of normal scores with zero mean, hence it is unclear why you get an average of -1. Note that if your variable takes only a few values or if there is a large proportion of data below the detection limit or equal to zero, a normal score transform that artificially despikes these similar values might not be the most appropriate approach.
Pierre Goovaerts <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> Dr. Pierre Goovaerts President of PGeostat, LLC Chief Scientist with Biomedware Inc. 710 Ridgemont Lane Ann Arbor, Michigan, 48103-1535, U.S.A. E-mail: [EMAIL PROTECTED] Phone: (734) 668-9900 Fax: (734) 668-7788 http://alumni.engin.umich.edu/~goovaert/ <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> On Mon, 16 Feb 2004, [ISO-8859-1] José Manuel Blanco Moreno wrote: > Hi, list, > I'm working on simulation (again) with sgsim (gslib) and I've found > something that troubles me... > I'm trying to simulate a variable that has a zero inflated distribution > (weed counts), and I proceed as follows: > -calculate the normal scores variogram for that variable. > -fit the model (the total sill sums slightly more than one) > -especify the details for simulation ... and run it. > > And then comes the problem: in the debugging file appears a rather > pretty question asking if the variance is near one (when it is clear it > is not; my variance is about TWO!) and if the mean is near zero (when, > again, it is not near zero, but near minus one). > I suppose that this is generated by that zero inflated distribution. > Is that true? > > Another question; Could this affect the validity of simulation? Should I > proceed in another way (v.g. Indicator simulation)? > > Thank you for any light shed on this question. > > -- > --------------------------------------- > José Manuel Blanco Moreno > > Dept. de Biologia Vegetal (Botànica) > Universitat de Barcelona > Av. Diagonal 645 > 08028 Barcelona > SPAIN > --------------------------------------- > > phone: (+34)93.402.1471 > fax: (+34)93.411.2842 > e-mail: [EMAIL PROTECTED] > > > > > -- > * To post a message to the list, send it to [EMAIL PROTECTED] > * As a general service to the users, please remember to post a summary of any useful > responses to your questions. > * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and > "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO > NOT SEND Subscribe/Unsubscribe requests to the list > * Support to the list is provided at http://www.ai-geostats.org > > -- * To post a message to the list, send it to [EMAIL PROTECTED] * As a general service to the users, please remember to post a summary of any useful responses to your questions. * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list * Support to the list is provided at http://www.ai-geostats.org
