# Create a variable with a reference to a specific country

After a previous post on mapping the Political Ties with Stata, let me show how to compute how to create an idea point relatively a specific country. This reasoning can be applied to different types of variables.

The first step is to create a variable that will serve as a reference. Here, it will be the ideal point of China. Save temporarily the data for China using tempfile idealnew. Don’t forget to run everything between preserve and restore. Then merge the ‘tempfile’ for China suing the temporal dimension and m:1 merge.

// Create a variable with a reference to specific country
preserve
keep if iso3=="CHN"
keep period_ idealnew
rename idealnew idealnewCHN
tempfile idealnew
save idealnew'
restore
merge m:1 period_ using idealnew'
drop _merge

Then, compute the distance to China and draw a graph. Here, I only used the data for the raw (non-smoothed) ideal points:

// Distance to China

xtset cn period_
xtdes

gen idealnewdistancetoCHN = idealnewCHN - idealnew ///
if idealnewCHN!=.

preserve
drop if period<=tm(1970m1)
keep if iso3=="USA" | iso3=="GBR" ///
| iso3=="CHN" | iso3=="DEU"
xtline idealnewdistancetoCHN, overlay legend(pos(6) cols(5)) ///
yline(0) ///
graphregion(margin(l+2 r+4)) ///
title(Ideal Distance to China Estimates: UN GA Voting Data)
graph rename Graph ideal_over_smoothed, replace
graph export figures\ideal_smoothed_overCHN.png, as(png) ///
width(4000) replace
graph export figures\ideal_smoothed_overCHN.pdf, as(pdf) ///
replace
restore

I am grateful to Andrew Musau for insightful answers on the Stata forum.

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