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st: Updates for nearstat and splagvar available for download


From   "P. Wilner Jeanty" <pwjeanty@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Updates for nearstat and splagvar available for download
Date   Mon, 26 Dec 2011 12:01:49 -0600

Hi All,

Thanks to Kit Baum, new versions for -nearstat- and -splagvar- are
available on SSC. Using Mata, the Stata’s new matrix language,
-nearstat- calculates distances, generates distance-based variables,
and exports the distances to a Stata matrix, a Mata file, or a text
file. To  generate the variables, nearstat performs, for each
observation in a georeferenced Stata dataset, a series of
computational tasks including, but not limited to, calculating
distance-weighted descriptive statistics over all neighbors, nearest
neighbors, and neighbors falling in a specified distance band;
calculating distance to nearest neighbors; counting the number of
neighbors falling in a specified distance band; and determining
whether a specified (e.g., first, second, third,…) nearest neighbor
falls within a certain distance band. Central to the power behind
-nearstat- is a striking Mata function, -minindex()-. Updates include
some fixes (e.g., display format when option des() is specified), an
option to request a variable holding the minimum or maximum distance
from each observation to its neighbors, and an option -iidist()- to
request a variable holding one-to-one distance (i.e., diagonal
elements) when latitudes and longitudes specified in -varlist1- are
different from those specified with the -near()- option.

-splagvar- generates spatially lagged variables of order up to 3,
constructs the Moran scatter plot, and calculates global Moran's I
statistics to test for the presence of spatial dependence in a
variable.  Spatially lagged variables can now be generated for a
specific equation when the equation(#) option is specified.  If
equation(#) option is specified, then -splagvar- form the names of the
spatially lagged variables by prefixing the names of the variables
whose spatial lags were taken with wy#_, wx#_, w2x#_, and w3x#_, where
# stands for the equation number. Otherwise, names are formed by
prefixing  the supplied variable names with wy_, wx_, w2x_, and  w3x_.

To install the new versions type the following command lines and then
restart Stata.

ssc install nearestat, replace
ssc install splagvar, replace



Best wishes,


Wilner




----------------------------
P. Wilner Jeanty
Rice University
MS 208 6100 Main Street Houston, TX 77005
Phone: (713) 348-3114
Email: pwjeanty@rice.edu
Web: http://www.kinder.rice.edu
           http://www.stasacode.com
           http://ideas.repec.org/e/pje95.html

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