[R] sem package subscript out of bounds error

Jarrett Byrnes jebyrnes at ucdavis.edu
Mon Nov 20 20:31:51 CET 2006


John,

Thank you so much.  That appears to have done the trick.  You're  
right about the non-association between previous year and current  
year variables - I'm early in model development and was  
troubleshooting to make sure nothing would cause any huge snafus, but  
those were indeed elements that were going to later appear in the model.

Thanks, though, for help with interpreting the error.  It saved my  
bacon, as it were!

One other quick question I had (and I was going to sit down tonight  
and see if I can implement this - if so, I'll send you the code) -  
would it be possible at all to implement comments within models in  
specify.model.  I know commenting up my model, partitioining it into  
blocks, would help me organizationally avoid these sorts of snafus.   
That, and an update.model would also make coding multiple models for  
comparison far far easier.  Again, if I end up getting to it first,  
as I'm sure you're rather busy, I'll let you know.

Thanks again for a great package - it's getting a workout over here,  
and I look forward to seeing how you continue to develop it!

-Jarrett

On Nov 20, 2006, at 6:07 AM, John Fox wrote:

> Dear Jarrett,
>
> Your observed-variable covariance matrix contains a variable,
> Prev.Year.Herbivore.Abundance, that doesn't appear in the model. I  
> agree
> that the error message that this produces is cryptic and will think  
> about
> how to improve that, or to allow the observed-variable covariance  
> matrix to
> contain variables not used in the model.
>
> Beyond that, the structure of the model seems odd to me: (1) The model
> implies that the exogenous variables  
> (Prev.Year.Predatory.Invert.Abundance,
> Prev.Year.Predatory.Fish.Abundance, and Mean.Temp.C, if I read the  
> model
> right) are uncorrelated with each other. You could specify  
> covariances among
> these variables, or, more simply, use the fixed.x argument to sem(). 
> (2)
> Errors for similar endogenous variables in different years are  
> uncorrelated
> (e.g., for Prev.Year.Kelp.Abundance, Kelp.Abundance), and two  
> variables
> taken to be exogenous are uncorrelated with the errors of the same  
> variables
> in the subsequent year (Prev.Year.Predatory.Invert.Abundance,
> Prev.Year.Predatory.Fish.Abundance). (3) Again if I read the  
> structure of
> the model right, it seems to be recursive, in which case least-squares
> regression would give you the same estimates as the FIML estimates  
> provided
> by sem().
>
> I hope this helps,
>  John
>
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> Canada L8S 4M4
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox
> --------------------------------
>
>> -----Original Message-----
>> From: r-help-bounces at stat.math.ethz.ch
>> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Jarrett Byrnes
>> Sent: Monday, November 20, 2006 12:32 AM
>> To: R-help at stat.math.ethz.ch
>> Subject: [R] sem package subscript out of bounds error
>>
>> I'm having the most curious error while using the sem
>> package.  For the model I'm working with, I keep getting the
>> following error:
>>
>> Error in J[cbind(1:n, observed)] <- 1 : subscript out of bounds
>>
>>
>> I''ve used debug=TRUE with sem, and there don't appear to be any
>> problems with model - there are no latent variables in this model.
>> The variables in the covariance matrix are all in the model.
>> I've tried this with simpler version of the below model, and
>> keep getting the same error.
>>
>> What does this error mean?
>>
>> Below is the full code, but I've tried this with all sorts of
>> subsets of the model, making sure to keep all of the proper
>> error terms.
>>
>> ---
>>
>> fish.invert.data<-data.frame(Prev.Year.Predatory.Invert.Abundance,
>> 						
>> Prev.Year.Predatory.Fish.Abundance,
>> 						
>> Predatory.Invert.Abundance,
>> 						
>> Predatory.Fish.Abundance,
>> 						
>> Prev.Year.Herbivorous.Invert.Abundance,
>> 						
>> Prev.Year.Herbivorous.Fish.Abundance,
>> 						
>> Herbivorous.Invert.Abundance,
>> 						
>> Herbivorous.Fish.Abundance,
>> 						Kelp.Abundance,
>> 						
>> Prev.Year.Kelp.Abundance,
>> 						Mean.Temp.C,
>> 						
>> Prev.Year.Herbivore.Abundance)
>>
>>
>> #na.rm=TRUE to deal with a few rows of missing data	
>> fish.invert.covar<-var(fish.invert.data, na.rm=TRUE)
>>
>> fish.invert.model<-specify.model()
>> Prev.Year.Predatory.Invert.Abundance ->
>> Prev.Year.Herbivorous.Invert.Abundance, pred.invert.top.down,
>> NA Predatory.Invert.Abundance ->
>> Herbivorous.Invert.Abundance, pred.invert.top.down, NA
>> Prev.Year.Predatory.Fish.Abundance ->
>> Prev.Year.Herbivorous.Fish.Abundance, pred.fish.top.down, NA
>> Predatory.Fish.Abundance -> Herbivorous.Fish.Abundance,
>> pred.fish.top.down, NA Prev.Year.Predatory.Fish.Abundance ->
>> Prev.Year.Herbivorous.Invert.Abundance,
>> pred.fish.invert.top.down, NA Predatory.Fish.Abundance ->
>> Herbivorous.Invert.Abundance, pred.fish.invert.top.down, NA
>> Prev.Year.Herbivorous.Fish.Abundance ->
>> Prev.Year.Kelp.Abundance, top.down.herb.fish, NA
>> Prev.Year.Herbivorous.Invert.Abundance ->
>> Prev.Year.Kelp.Abundance, top.down.herb.invert, NA
>> Herbivorous.Fish.Abundance -> Kelp.Abundance,
>> top.down.herb.fish, NA Herbivorous.Invert.Abundance ->
>> Kelp.Abundance, top.down.herb.invert, NA
>> Prev.Year.Kelp.Abundance -> Herbivorous.Fish.Abundance,
>> bottom.up.kelp.fish, NA Prev.Year.Kelp.Abundance ->
>> Herbivorous.Invert.Abundance, bottom.up.kelp.inverts, NA
>> Prev.Year.Herbivorous.Fish.Abundance ->
>> Predatory.Fish.Abundance, bottom.up.herb.fish, NA
>> Prev.Year.Herbivorous.Invert.Abundance ->
>> Predatory.Invert.Abundance, bottom.up.herb.invert, NA
>> Prev.Year.Herbivorous.Invert.Abundance ->
>> Predatory.Fish.Abundance, bottom.up.herb.invert.fish, NA
>> Mean.Temp.C -> Kelp.Abundance, mean.nutrients.from.temp, NA
>> Prev.Year.Predatory.Invert.Abundance ->
>> Predatory.Invert.Abundance, prev.year.pred.invert, NA
>> Prev.Year.Predatory.Fish.Abundance ->
>> Predatory.Fish.Abundance, prev.year.pred.fish, NA
>> Prev.Year.Herbivorous.Fish.Abundance ->
>> Herbivorous.Fish.Abundance, prev.year.herb.fish, NA
>> Prev.Year.Herbivorous.Invert.Abundance ->
>> Herbivorous.Invert.Abundance, prev.year.herb.invert, NA
>> Prev.Year.Kelp.Abundance -> Kelp.Abundance, prev.year.kelp,
>> NA Kelp.Abundance <-> Kelp.Abundance, kelp.abundance.error,
>> NA Prev.Year.Kelp.Abundance<-> Prev.Year.Kelp.Abundance,
>> prev.year.kelp.error, NA Mean.Temp.C <-> Mean.Temp.C,
>> mean.temp.error, NA Prev.Year.Herbivorous.Fish.Abundance <->
>> Prev.Year.Herbivorous.Fish.Abundance, prev.herb.fish.error,
>> NA Prev.Year.Herbivorous.Invert.Abundance <->
>> Prev.Year.Herbivorous.Invert.Abundance,
>> prev.herb.invert.error, NA Prev.Year.Predatory.Fish.Abundance
>> <-> Prev.Year.Predatory.Fish.Abundance, prev.pred.fish.error,
>> NA Prev.Year.Predatory.Invert.Abundance <->
>> Prev.Year.Predatory.Invert.Abundance, prev.pred.invert.error,
>> NA Herbivorous.Fish.Abundance <->
>> Herbivorous.Fish.Abundance,herb.fish.error, NA
>> Herbivorous.Invert.Abundance <->
>> Herbivorous.Invert.Abundance, herb.invert.error, NA
>> Predatory.Fish.Abundance <-> Predatory.Fish.Abundance,
>> pred.fish.error, NA Predatory.Invert.Abundance <->
>> Predatory.Invert.Abundance, pred.invert.error, NA
>>
>> fish.invert.model
>>
>> fish.invert.sem<-sem(fish.invert.model, fish.invert.covar, N=166,
>> debug=TRUE)
>>
>>
>> Yields
>>
>> observed variables:
>> [1] "1:Prev.Year.Predatory.Invert.Abundance"
>> "2:Prev.Year.Predatory.Fish.Abundance"
>> "3:Predatory.Invert.Abundance"
>> [4] "4:Predatory.Fish.Abundance"
>> "5:Prev.Year.Herbivorous.Invert.Abundance"
>> "6:Prev.Year.Herbivorous.Fish.Abundance"
>> [7] "7:Herbivorous.Invert.Abundance"
>> "8:Herbivorous.Fish.Abundance"             "9:Kelp.Abundance"
>> [10] "10:Prev.Year.Kelp.Abundance"
>> "11:Mean.Temp.C"
>> "12:Prev.Year.Herbivore.Abundance"
>>
>>
>> parameters:
>> [1] "1:pred.invert.top.down"        "2:pred.fish.top.down"
>> "3:pred.fish.invert.top.down"   "4:top.down.herb.fish"
>> [5] "5:top.down.herb.invert"        "6:bottom.up.kelp.fish"
>> "7:bottom.up.kelp.inverts"      "8:bottom.up.herb.fish"
>> [9] "9:bottom.up.herb.invert"       "10:bottom.up.herb.invert.fish"
>> "11:mean.nutrients.from.temp"   "12:prev.year.pred.invert"
>> [13] "13:prev.year.pred.fish"        "14:prev.year.herb.fish"
>> "15:prev.year.herb.invert"      "16:prev.year.kelp"
>> [17] "17:kelp.abundance.error"       "18:prev.year.kelp.error"
>> "19:mean.temp.error"            "20:prev.herb.fish.error"
>> [21] "21:prev.herb.invert.error"     "22:prev.pred.fish.error"
>> "23:prev.pred.invert.error"     "24:herb.fish.error"
>> [25] "25:herb.invert.error"          "26:pred.fish.error"
>> "27:pred.invert.error"
>>
>>
>> RAM:
>>        heads to from parameter start
>> [1,]     1  5    1         1    NA
>> [2,]     1  7    3         1    NA
>> [3,]     1  6    2         2    NA
>> [4,]     1  8    4         2    NA
>> [5,]     1  5    2         3    NA
>> [6,]     1  7    4         3    NA
>> [7,]     1 10    6         4    NA
>> [8,]     1 10    5         5    NA
>> [9,]     1  9    8         4    NA
>> [10,]     1  9    7         5    NA
>> [11,]     1  8   10         6    NA
>> [12,]     1  7   10         7    NA
>> [13,]     1  4    6         8    NA
>> [14,]     1  3    5         9    NA
>> [15,]     1  4    5        10    NA
>> [16,]     1  9   11        11    NA
>> [17,]     1  3    1        12    NA
>> [18,]     1  4    2        13    NA
>> [19,]     1  8    6        14    NA
>> [20,]     1  7    5        15    NA
>> [21,]     1  9   10        16    NA
>> [22,]     2  9    9        17    NA
>> [23,]     2 10   10        18    NA
>> [24,]     2 11   11        19    NA
>> [25,]     2  6    6        20    NA
>> [26,]     2  5    5        21    NA
>> [27,]     2  2    2        22    NA
>> [28,]     2  1    1        23    NA
>> [29,]     2  8    8        24    NA
>> [30,]     2  7    7        25    NA
>> [31,]     2  4    4        26    NA
>> [32,]     2  3    3        27    NA
>> Error in J[cbind(1:n, observed)] <- 1 : subscript out of bounds
>>
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