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From |
James Cross <jcross@tcd.ie> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Weighted Euclidean distances with panel data |

Date |
Wed, 9 Sep 2009 17:16:57 +0100 |

The actual calculation for each element in the vector I am looking to produce is simply the reference point minus the position. Interesting that you suggest it might be possible using -reshape-. I am not sure if I can go down this route as the next step, once I have produced the vector is to multiply it by its transpose and a diagonal vector of dimensional saliencies (this is part of the formula for calculating weighted euclidean distances over multiple dimensions). I have not used Mata before so I think I better start familiarising myself with it! Thanks, James 2009/9/9 Austin Nichols <austinnichols@gmail.com>: > James Cross<jcross@tcd.ie> : > 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<jcross@tcd.ie> 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/ > > -- James Cross Department of Political Science Trinity College 2-3 College Green Dublin 2 Republic of Ireland Mobile: +353 (0) 85 74 88 330 Email: jcross@tcd.ie * * 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/

**Follow-Ups**:**Re: st: Weighted Euclidean distances with panel data***From:*Austin Nichols <austinnichols@gmail.com>

**References**:**st: Weighted Euclidean distances with panel data***From:*James Cross <jcross@tcd.ie>

**Re: st: Weighted Euclidean distances with panel data***From:*Austin Nichols <austinnichols@gmail.com>

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