James Cross<[email protected]> :
This would be fairly easy to program in Mata, but you can also
-reshape- to wide format and calculate the distances using -generate-
if you know how you are going to treat missing values. Once you can
specify the actual calculations for your example, it will be easier to
specify a method.
On Wed, Sep 9, 2009 at 9:12 AM, James Cross<[email protected]> wrote:
> Hi all,
>
> I have a large panel dataset which contains information on different
> actor positions on different issues (dimensions) within different
> legislative proposals. Each actor position has a saliency score
> associated with the position by which I hope to weight the importance
> of the issue/dimension to that actor. In essence, I am trying to
> calculate the weighted Euclidean distances between each actors'
> position and a reference point.
>
> In order to do this I first need to create submatrices of the dataset,
> structured as row vectors, that contain the distances between the two
> points of interest for each actor for each issue/dimension for each
> proposal. That is, I should end up with a row vector for each actor of
> distances between the actors' position and the reference point. The
> number of elements in this row vector is determined by the number of
> issues in each proposal in the panel data. While I can do this for
> each observation individually, I am wondering if it is possible to get
> stata to do it automatically to save me the effort.
>
> The resulting vector will then need to be multiplied by its transpose
> and a diagonal matrix of issue salience for each actor but that cannot
> be done until I have created the individual actor distance vectors.
> There is also an issue with missing data in that sometimes the
> reference point will be missing and some actors will not have
> positions on all of the issues/dimensions.
>
> The data is structured as follows:
>
>
> proposal issue actor position ref point
> 04163 1 1 0 0
> 04163 2 1 0 0
> 04163 1 2 0 0
> 04163 2 2 0 0
> 00032 1 1 100 0
> 00032 2 1 50 n/a
> 00032 3 1 100 100
> 00032 4 1 100 0
> 00032 1 2 100 0
> 00032 2 2 0 n/a
> 00032 3 2 0 100
> 00032 4 2 0 0
> 00032 1 3 40 0
> 00032 2 3 100 n/a
> 00032 3 3 100 100
> 00032 4 3 100 0
>
> The resulting vector would look like this for proposal 00032 actor 1:
> [100 n/a 0 100], and for proposal 04163 actor 1: [0 0].
>
> I am not sure if this is even possible in stata or if it is, how much
> programming is involved.
>
> Any suggestions welcome.
> Thanks in advance.
>
> James
>
*
* 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/
