[R] need help with errors in betareg analysis

[knussear]

Yes, fair enough. I wasn't sure it was fitting the mode at all, but here is
an example of what I see

> model <- betareg(ACT ~ ST+DOY, data = actDL_F)
Warning messages:
1: In sqrt(diag(fisherinv)) : NaNs produced
2: In sqrt(diag(fisherinv)) : NaNs produced
3: In sqrt(W) : NaNs produced
4: In sqrt(W) : NaNs produced
5: In sqrt(1 + phihat) : NaNs produced



Call:
betareg(formula = ACT ~ ST + DOY, data = actDL_F)

Coefficients:
(Intercept)           ST          DOY          phi  
  1.780e+07   -1.149e+09    2.225e+08   -4.090e+08  

So I don't see a W listed, but the phi is going negative just as you
suggested.

So are the results wonky if phi is negative?



Ben Bolker wrote:
> 
> knussear <knussear <at> mac.com> writes:
> 
>> 
>> 
>> Hi
>> 
>> I'm trying to fit a model in betareg and I'm getting errors, but have no
>> idea what they mean or how to solve them. Does anyone have experience
>> with
>> this?
>> 
>> > model <- betareg(ACT ~ ST*SoilT, data = actDL_F)
>> Warning messages:
>> 1: In sqrt(W) : NaNs produced
>> 2: In sqrt(W) : NaNs produced
>> 3: In sqrt(1 + phihat) : NaNs produced
>> 
>> data summaries don't give any na's or problems I can see
>> 
>> > summary(actDL_F$ACT)
>>      Min.   1st Qu.    Median      Mean   3rd Qu.      Max. 
>> 0.0006227 0.0505600 0.2163000 0.2643000 0.4084000 0.9994000 
>> 
>> > summary(actDL_F$ST)
>>    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
>>   8.085  29.560  34.760  33.870  39.430  49.610 
>> 
>> > summary(actDL_F$SoilT)
>>    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
>>   17.42   20.95   24.18   24.26   27.21   31.19 
>> 
>> Thanks
>> 
>> Ken
> 
>  Note that these results are from the contributed "betareg"
> package, so if my answer doesn't do it for you, you could
> contact the package authors (see help(package="betareg") ).
> Also note that you haven't given us a reproducible example,
> so there's no way we can say for sure.
> 
>   That said: it seems *likely* (take my word for it
> at your own risk) that W (whatever it is) and phihat
> (whatever it is) are not constrained to be positive,
> so they might wander negative in the course of the
> optimization.  If this is not fatal to
> the optimization process, then you can still arrive
> at a reasonable solution where they are all positive.
> There doesn't seem to be see any "trace" option in
> betareg, so it will be a little harder to see what's
> going on.
> 
>  It's not wonky data I would worry about, but wonky
> results (which you haven't shown us).
> 
>    Ben Bolker
> 
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
> 
> 

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