[R-sig-Geo] Problem with moran.test function

[Roger Bivand]

On Thu, 17 Jun 2010, Michael Haenlein wrote:

> Dear Roger,
>
> As per your suggestion, I moved back to spdep, version 0.5-11, 2010-05-31.
>
> Based on your message I think the problem might have been that the input
> file only had two columns and not three. As you might remember from some
> previous conversations we had, I'm using spdep in the context of social
> network analysis. So my initial input file only included information on who
> is connected to whom (e.g., "2 3" or "5 7") but not on how strong/ weak that
> connection is. I now included a third column that has the value 1 for all
> pairs (e.g., "2 3 1" or "5 7 1") and reading now works fine. Probably
> another indication that the read.dat2listw() function had some problems in
> the previous version.
>
> Within the new version of spdep also my estimation of Moran's I now works
> perfectly fine:
>
> Moran I statistic       Expectation          Variance
>     0.0191115263     -0.0002926544      0.0003092456
>
> So I think the issue is solved. If you still would like to look at the input
> files, please let me know and I'm happy to send them to you off-list.

I think the missing column is the key here, so I'll add a check to 
read.dat2listw().

Thanks,

Roger

>
> Thanks again for your help -- I appreciate a lot!
>
> Michael
>
>
>
>
>
> -----Original Message-----
> From: Roger Bivand [mailto:Roger.Bivand at nhh.no]
> Sent: Thursday, June 17, 2010 08:50
> To: Michael Haenlein
> Cc: r-sig-geo at stat.math.ethz.ch
> Subject: Re: [R-sig-Geo] Problem with moran.test function
>
> On Thu, 17 Jun 2010, Michael Haenlein wrote:
>
> No, it is definitely better to find out what is wrong with Network.txt, as
> the change made in April to sn2listw() - called by read.dat2listw() was to
> trap defective input objects. Please look at traceback() after the error.
> Do debug() on read.dat2listw, and summary() on wmat and sn. Are there
> locale issues in reading the text file, perhaps (decimal symbol?)?
>
> This would feed downstream into the obviously wrong lagged values seen
> below. I'd be interested in access to the input file to strengthen defences
> against unusual weights, or weights seen by the system as unusual. I think
> that an errant final column is becoming a factor, then converted to numeric
> (with large n and many unique weights, their integer indices will become
> large). read.dat2listw() needs to check that there are 3 columns, and that
> the first two are integer, and the third is numeric, I think. But we need to
> see why reading the file is failing.
>
> Roger
>
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>
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no