error of "spmatrix create contiguity"

[Miranda Uchii]

Hello everyone,

I am trying to run a model with spatial lags of the dependent variable using spxtregress in Stata 17. I would like to create a neighbor contiguity matrix.

I have two datasets. For the first, I have the variables of coordinates like; _ID, _CY and _CX with observations of 54 African countries. The second, I have my panel data with 864 observations from 2003 to 2018.
My code used is;
merge m:1 country using “shp_59_country2.dta”
The results are 864 observations matched.
But when I use this code; “spmatrix create contiguity W"
Stata said “Some observations in master dataset are not in coordinates dataset” r(498);

Could somebody help me with this problem?
What have I been doing wrong?

Thank you.

[Andrew Musau]

Two issues that I see:

1. As you have panel data, you cannot create the weighting matrix directly. The manual states:

If you have panel data and want to create a weighting matrix, you must use an if statement with spmatrix create to restrict the data to a single time value.

2. The error message indicates that there are some identifiers in "shp_59_country2.dta" not present in your shapefile. So check for missing values or extra identifiers across the two datasets.

[Miranda Uchii]

Dear Andrew Musau

Thank you very much for your response.

I have looked into all the missing values and adjusted them to eliminate them.
However, that method did not work.

On the other hand, I didn't know that I cannot create the weighting matrix directly.
I appreciate the very useful information you have given me.
Could you please tell me from which page I can find the manual so that I can get more detailed information?

Thank you.

[Andrew Musau]

Here is the link to the PDF manual entry for the command: https://www.stata.com/manuals/spspmatrixcreate.pdf. If you are able to share the datasets, I will be happy to have a look.

[Miranda Uchii]

I am so sorry for the delayed response.

I tried using the if command as you advised, but it did not work very well. I'm sorry for all your efforts.

I have attached the data set.
I would be very happy if you could take a look at the data. I would appreciate any advice you could give me.

[Andrew Musau]

Attach the shapefile as well.

[Miranda Uchii]

Ok. I don't know why but I could not upload my file, so I would like you to download shapefile from this page; https://open.africa/dataset/africa-shapefiles

[Andrew Musau]

OK, will have a look and get back to you.

[Andrew Musau]

I am so sorry for the delayed response.

I tried using the if command as you advised, but it did not work very well. I'm sorry for all your efforts.

I have attached the data set.
I would be very happy if you could take a look at the data. I would appreciate any advice you could give me.

It may be something with your shapefile. Try this:

//https://open.africa/dataset/africa-shapefiles
copy https://open.africa/dataset/dacf49f9-c71d-4a70-80c5-7b4afe1a5dc0/resource/04ed7565-614d-473e-88b9-2e9208c5cece/download/afr_g2014_2013_0.zip afr_g2014_2013_0.zip, replace
unzipfile afr_g2014_2013_0.zip, replace
spshape2dta afr_g2014_2013_0, replace

tempfile afrshape
use  afr_g2014_2013_0.dta , clear
replace ISO3= string(_n) if missing(ISO3)
save `afrshape'

use "shp_59_country2_1134_sodan.dta", clear
assert countrycode==ISO3
drop _ID- MOI
rename countrycode ISO3
merge m:1 ISO3 using `afrshape', keep(master match) nogen
xtset _ID year
spmatrix create contiguity W if year==2000
spset

and you should get

. spmatrix create contiguity W if year==2000
  weighting matrix in W contains 7 islands

. spset
  Sp dataset shp_59_country2_1134_sodan.dta
                data:  panel
     spatial-unit id:  _ID (equal to country)
             time id:  year (see xtset)
         coordinates:  _CY, _CX (latitude-and-longitude, miles)
    linked shapefile:  afr_g2014_2013_0_shp.dta