glm error message when using family Gamma(link="inverse")
On Tue, 9 Dec 2008, John Sorkin wrote:
It appears that I have sinned and for this I surely will wear sack cloth and grovel until my period of penitence is fulfilled. I update R and my problem remains. Please see code snippet (as per posting guidelines) below R 2.8.0 windows XP
summary(data$AAMTCAREJ)
Min. 1st Qu. Median Mean 3rd Qu. Max.
1.0 404.3 1430.0 6567.0 5457.0 327900.0
fitglm<-glm(AAMTCAREJ~sexcat+H_AGE+SmokeCat+InsuranceCat+MedicadeCat+
+ incomegrp+racecat+MARSTATJS+EdCat+bmiNewjohn,data=data,family=Gamma(link = "inverse")) Error: no valid set of coefficients has been found: please supply starting values In addition: Warning message: In log(ifelse(y == 0, 1, y/mu)) : NaNs produced
Well, this still isn't something others can _reproduce_ , but... The error message seems to be from glm.fit(). I'd guess you are throwing glm() a knuckleball and it is choking on its attempt to calculate the deviance - note the warning message. You might be able to calm glm()'s frayed nerves by supplying some decent start values as it is asking. Possibly starting with a subset of variables, using the coef()s for the subset and setting the others to zero when you attempt to fit all together will be enough to push it past its sticking point. HTH, Chuck
John David Sorkin M.D., Ph.D. Chief, Biostatistics and Informatics University of Maryland School of Medicine Division of Gerontology Baltimore VA Medical Center 10 North Greene Street GRECC (BT/18/GR) Baltimore, MD 21201-1524 (Phone) 410-605-7119 (Fax) 410-605-7913 (Please call phone number above prior to faxing)
Prof Brian Ripley <ripley at stats.ox.ac.uk> 12/9/2008 2:11 PM >>>
On Tue, 9 Dec 2008, John Sorkin wrote:
R 2.5
Please 1) do as the posting guide asks, and quote version numbers accurately. 2) do as the posting guide asks, and update *before* posting. That's too old a version to support here.
windows XP I am getting an error from glm() that I don't understand. Any help or suggestions would be appreciated. N.B. 1<=AAMTCAREJ<=327900
summary(data$AAMTCAREJ)
Min. 1st Qu. Median Mean 3rd Qu. Max.
1.0 404.3 1430.0 6567.0 5457.0 327900.0
fitglm<-glm(AAMTCAREJ~sexcat+H_AGE+SmokeCat+InsuranceCat+MedicadeCat+
+ incomegrp+racecat+MARSTATJS+EdCat+bmiNewjohn,data=data,family=Gamma(link = "inverse")) Error: no valid set of coefficients has been found: please supply starting values In addition: Warning message: NaNs produced in: log(x)
That model is not necessarily valid: the linear predictor has to be strictly positive. If you really know why it is applicable you will be able to give starting values (e.g. maybe all the columns of the design matrix are positive, in which case you will be able to find suitable positive initial coefficients).
Thanks
John
John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)
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