Prof. Blackwell,
Thank you for your assistance with saving priors. I've subsequently attempted to run
Aemliaview and have recieved an error similar to Prof. Saunder's (the difference is
which order's minor is not positive. Mine are generally 4 and 6). I've tried
constructing my prior matrix in various different ways with different variables, but
always end up with the same result. Not even my attempts at using a single prior at a time
worked.
I've attempted to run the program several times on the same data set using the same
prior, and it appears to occur at different points during the first round of imputations.
Generally, it seems to occur as the output hits 600 or so, although it has occurred as
late as 2234.
My data is a bit too varied and complex to be easily described, so I can e-mail a copy of
my dataset if that would be useful.
As always your help and dedication are greatly appreciated,
-IM
---quote---
Matthew,
Thank you for updating the software so quickly. I emailed before that
I had the same problem as Heather. I just ran my imputations with
range priors set and received the following error in the output window
after the 4th imputation (of 5):
There was an unexpected error in the execution of Amelia.
Double check all inputs for errors and take note of the error message:
Error in chol(copy.theta[c(FALSE, m[ss, ]), c(FALSE, m[ss, ])]) :
the leading minor of order 28 is not positive definite
This is the same error I received before except the order number given
is not always the same (I tried several different variations).
Repeating the imputations with a ridge prior results in the same error
following the iterations of imputation 2:
There was an unexpected error in the execution of Amelia.
Double check all inputs for errors and take note of the error message:
Error in chol(copy.theta[c(FALSE, m[ss, ]), c(FALSE, m[ss, ])]) :
the leading minor of order 22 is not positive definite
The variables for which I set range priors are continuous and ordinal,
though I am considering the ordinal variables to be continuous. One
ranges from -2.5 to 2.5 and only has 15 of 208 cases missing, and the
others from 0 to 2 with a bit more missing cases (about 60 each).
Let me know if you need more details.
Thank you,
Erin Saunders
Portland State University
On 3/12/07, Matthew Blackwell <blackwel@xxxxxxxxxxxxxxx> wrote:
Hello Heather,
Sorry for the late response, but I wanted to let you know that we've fixed
the error in Amelia you described where the mean of the prior would be set
to the maximum in the range. You can update your copy of Amelia by running
the following line of code in R:
install.packages("Amelia", repos="http://gking.harvard.edu";)
Also, I wonder if you could see if this solves your other error message
about the leading minor not being positive definite. If it doesn't, please
send us another message with a bit more detail about your data and the
conditions of the error message.
thanks for helping us out,
matt.
On Mon, 5 Mar 2007, Heather Stoll wrote:
Dear all,
I'm running version 1.1-20 of Amelia on a Windows system. In trying to help
a student add a range prior for an entire variable using AmeliaView, I
clicked on "Set observation priors"; then "add range prior"; and in
the "add
prior" dialogue box that pops up, selected as "case" the whole variable,
selected the appropriate variable, set the minimum and maximum, entered an
appropriate confidence coefficient, and then clicked "OK". In the
"Observational Priors" window, what's now listed is a whole variable
prior
with a mean equal to the maximum value that I fed to the range prior. This
doesn't seem right. I'm wondering either if I'm missing something or if
this
is just a display issue. I haven't yet tried to multiply impute this data
set in R itself (and hence to build the desired prior matrix).
Any thoughts would be much appreciated.
Heather Stoll
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