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Re: st: calculating many distances and storing them in many new variables
From
Yuval Arbel <[email protected]>
To
[email protected]
Subject
Re: st: calculating many distances and storing them in many new variables
Date
Fri, 21 Oct 2011 10:40:06 +0200
Anna,
I'm not sure what your precise goal is. But if your target is only to
map what hospital each patient went, may I suggest the following:
Suppose you have a column of coordinates under "patient" and another
column under "hospitals"
If you are working with STATA11 you can try running:
reg patient i.hospitals
Let me show you what is the output you get by using one of the
examples I ran: I collected a small dataset, which measures land
values (rent) and distance from Tel Aviv center (distance):
. reg rent i.distance
Source | SS df MS Number of obs = 55
-------------+------------------------------ F( 9, 45) = 12.43
Model | 294279904 9 32697767.1 Prob > F = 0.0000
Residual | 118368183 45 2630404.07 R-squared = 0.7131
-------------+------------------------------ Adj R-squared = 0.6558
Total | 412648087 54 7641631.24 Root MSE = 1621.9
------------------------------------------------------------------------------
rent | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
distance |
1000 | -8245.833 1238.71 -6.66 0.000 -10740.72 -5750.943
1500 | -8087.026 1038.817 -7.78 0.000 -10179.31 -5994.741
2000 | -6353.833 1067.634 -5.95 0.000 -8504.158 -4203.509
2500 | -7560.333 1480.542 -5.11 0.000 -10542.3 -4578.37
3000 | -6545.958 1097.999 -5.96 0.000 -8757.442 -4334.475
3500 | -9500 1324.237 -7.17 0.000 -12167.15 -6832.85
4000 | -9891.905 1119.184 -8.84 0.000 -12146.06 -7637.752
4500 | -10258.33 1238.71 -8.28 0.000 -12753.22 -7763.443
5000 | -11600.33 1872.753 -6.19 0.000 -15372.25 -7828.414
|
_cons | 13433.33 936.3767 14.35 0.000 11547.37 15319.29
------------------------------------------------------------------------------
Note that the distance variable includes values from 500 to 5000
meters. The command made the 500 meter distance the base category.
On Fri, Oct 21, 2011 at 5:13 AM, Maria Ana Vitorino
<[email protected]> wrote:
> Dear StataList users,
>
> Suppose we have the following toy data which has a list with patients, the
> hospital to which they went (hosp_ch) and the coordinates for both.
>
> patient_id hosp_ch lat_pat lng_pat lat_hosp lng_hosp
> 1 a 2 4 5
> 6
> 2 a 1 3 5
> 6
> 8 c 3 5 10
> 12
> 9 a 5 2 5
> 6
> 12 b 8 6 8
> 9
>
>
> What I would like to do is:
> **To create new variables with the distances from every patient to every
> possible hospital in the data. So, I would like 3 new columns which will
> contain the distance from each patient to each hospital in the data.
> **Also, I would like to have those new columns labeled dist_a, dist_b and
> dist_c.
>
> Is there an efficient way to achieve this?
> In the real data, I have many more patients and hospitals (hundreds in fact)
> so I would like to generate these variables in an as automated way as
> possible.
>
> Any help is appreciated.
> Thanks!
> Ana
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> *
> * 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/
>
--
Dr. Yuval Arbel
School of Business
Carmel Academic Center
4 Shaar Palmer Street, Haifa, Israel
e-mail: [email protected]
*
* 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/