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singular convergence warning

2 messages · Price, Emily, Roman Luštrik

Original
Price, Emily
# 
Dear R mixed models users,

I'm running a Monte Carlo simulation with 16 cells using four loops to determine how sample size influences treatment effectiveness in single case design.  I'm running 1,000 replications for each cell so I have a total of 16,000 simulated datasets.  In 50 of the 16,000 datasets I'm getting the following warning message: In mer_finalize(ans) : singular convergence (7).  I would like to determine where the errors are occurring (i.e., which cells) so that I can do some follow up analyses but  I don't know  how to program a statement to tell me.  To let me know when each sample is finished within a cell I'm using the command:  cat("Iteration",i1,i2,i3,i4,t,"successful","\n") where i1, i2, i3, and i4 are the counters for each for loop and t is the value for the replication number within each cell.  Therefore, does anyone know how to use command cat to print the values of the specific cell when the warning message occurs? Or alternatively if there is a different way I would welcome that as well.  If you would like additional information about the code I can supply that as well.

Thanks!
Emily

Emily A. Price, PhD
Educational Research and Evaluation
Patton College of Education
Ohio University
Roman Luštrik
# 
This isn't exactly mixed-mo list material (try
http://stackoverflow.com/questions/tagged/r), but here goes.

R uses a mechanism to catch warnings and lets you print whatever you want
when this happens. For your convenience function `tryCatch` may be used.
With it, you evaluate an expression and should an error or a warning occur,
do something with it.
Here's an example of `tryCatch` in action. Notice the structure of `x` and
`y`, which you can use to extract the desired elements and handle the
situation further.
FWIW, you can have both, warning and error, in the same `tryCatch` call.
e)
function(w) w)
<simpleError: this is a simple error>
<simpleWarning: this is a simple warning>
List of 2
 $ message: chr "this is a simple error"
 $ call   : NULL
 - attr(*, "class")= chr [1:3] "simpleError" "error" "condition"
List of 2
 $ message: chr "this is a simple warning"
 $ call   : NULL
 - attr(*, "class")= chr [1:3] "simpleWarning" "warning" "condition"

HTH,
Roman
On Sun, Oct 12, 2014 at 10:08 PM, Price, Emily <ep311508 at ohio.edu> wrote: