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From |
max r <maxr28@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: spatial weighting matrix |

Date |
Wed, 8 Apr 2009 15:08:58 -0400 |

Kyle and Nick, Thank you for the suggestions. This is what I have done since the last email. Some one pointed me towards a spatial analysis software "GEODA" - it's free, and does spatially weighted regressions. I have linked the cross sectional version of my panel to a parcel map, after some tinkering around, was able to use this software to create queen contiguity weighting matrix. The weighting matrix is stored ".gal" or ".gwt" format , I currently wondering how to export the information about neighbors back into STATA. If my understand is correct, the weighting matrix, has i x i dimension, i= parcel, a cell value at the intersection of row I and column 2, takes 1 if parcel 1 is adjacent to parcel 2, and so on. thanks, Max On Wed, Apr 8, 2009 at 2:07 PM, Kyle Hood <kyle.hood@yale.edu> wrote: > I think you are absolutely right; computing a county-level weight matrix > without sparse matrix operators would be slow, to stay the least. > Via Austin Nichols' post I just noticed that there is a package usswm that > contains/computes contiguity spatial weight matrices for US states and > counties. I would play around with that, maybe. > > Nick Cox wrote: >> >> I think that's all correct, but one extra detail may bite. For example, >> a common size of problem is all 3000 or so counties in the USA. For >> coding contiguities for that, you really need to have or to mimic sparse >> matrix routines. >> Nick n.j.cox@durham.ac.uk >> Kyle Hood >> >> Thanks for the explanation of queen - I do recall that chess references >> are used, now; I guess I had forgotten since I have never based a weight >> >> matrix on contiguity. >> >> I am a little confused about what the asker wants from Stata, here. He >> says he has addresses (points), but wants a weighting matrix that depends on >> contiguity, which only makes sense for areal data. If these addresses >> contain the areas in question (for example, zip codes or states) then no >> geocoding is necessary -- one must simply extract the areas from the address >> data. However, after that, the information concerning which areas are >> adjacent to others is needed. I can't imagine that Stata can be used to >> obtain this information. If the asker >> >> has this information already, then it would of course be trivial to >> program the weighting matrix in Stata (using Mata or not). >> >> If the addresses do not contain the areas in question (for example, the >> asker wishes to consider adjacent census tracts, but has street address >> data), then the address information will have to be geocoded. The geocoded >> data must then be matched up with a map of census tracts based on location. >> In addition, information on which census tracts were adjacent would be >> needed, and this presents the same problem as above. >> >> Some of this can be done in Stata, but there are pieces that other >> software is better suited to deal with. >> >> Nick Cox wrote: >> >>> >>> The queen terminology in spatial analysis comes via chess. >>> Imagine squares on a chessboard. >>> A queen can enter a neighbouring square either across a length of >>> boundary (over a link or edge in a boundary network) or diagonally (if >>> two areas touch at a vertex or node in a boundary network). >>> A rook or castle is limited to the first of those. >>> In chess there are of course also other rules but they do not enter >>> here. >>> Thus "queen" implies contiguity wide sense and "rook" strict sense. >>> The terminology goes back at least as far as the work of geographer >>> Andrew Cliff and econometrician-statistician Keith Ord in the late >>> 1960s. >>> In terms of the question, I implemented weighting matrices via string >>> variables [!!!] in -spautoc- on SSC in 1997, but I'd do it in Mata >>> >> >> now, >> >>> >>> but I don't have detailed advice, let alone code. >>> Nick n.j.cox@durham.ac.uk >>> Kyle Hood >>> >>> >>> I'm not sure what "first-order queen contiguity" is, but you will >>> probably have to geocode address data (geocode: address->lat/lon), and >>> >> >> I >> >>> >>> don't think you can do this in Stata (that is, unless the breadth of >>> Stata's capabilities is larger than I had realized, which is sometimes >>> >> >> >>> >>> the case). Try ArcGIS. Once you have the geocoded data, you can >>> probably compute the weight matrix in Stata, if you want. >>> >>> max r wrote: >>> >>> >>>> >>>> I need to create a spatial weighting matrix (first-order queen >>>> contiguity) for a unbalanced panel dataset. The dataset has address >>>> information in it. Is there a way to do this in STATA? I am trying to >>>> test for neigborhood effects in behavior. Appreciate your thoughts. >>>> >>> >>> * >>> * For searches and help try: >>> * http://www.stata.com/help.cgi?search >>> * http://www.stata.com/support/statalist/faq >>> * http://www.ats.ucla.edu/stat/stata/ >>> >> >> >> > > > -- > Kyle Hood > Department of Economics > Yale University > New Haven, CT > website: http://www.econ.yale.edu/~kkh25/ > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: spatial weighting matrix***From:*max r <maxr28@gmail.com>

**Re: st: spatial weighting matrix***From:*Kyle Hood <kyle.hood@yale.edu>

**RE: st: spatial weighting matrix***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: spatial weighting matrix***From:*Kyle Hood <kyle.hood@yale.edu>

**RE: st: spatial weighting matrix***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: spatial weighting matrix***From:*Kyle Hood <kyle.hood@yale.edu>

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