README for DICL Database

Description:
	The Domestic and International Common Language (DICL) database contains a collection of country-level and bilateral 
    measures of language connections. The 8 DICL indices reflect multiple dimensions of linguistic relationships between 
    populations, including common official languages, common spoken languages, and intelligibility between different 
    languages. Several measures also differentiate between native languages and acquired languages.

Licensing:
	CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/).

Recommended citation:
	Gurevich, T., P.R. Herman, F. Toubal, and Y.V. Yotov. (2024) "The Domestic and International Common 
    Language (DICL) Database." USITC Economics Working Paper 2024-03-A.

Contents:
	The DICL database contains 12 columns and 58,564 rows comprised of indices for 29,403 unique country pairs. For 
    convenience, the international records are mirrored so that there is a record for both the pair (i, j) and (j, i). 
    The domestic records appear once for each country (2 * 29,161 mirrored international records + 242 domestic measures 
    = 58,564 total records). The 12 columns contain each of the 8 language measures described in the previous section 
    as well as names and ISO 3-digit alpha identifiers for each country. The first row of each column contains a column label.

Variables:
	iso3_i:	Country i ISO 3-digit alpha identifier
	country_i:	Country i name
	iso3_j:	Country j ISO 3-digit alpha identifier
	country_j:	Country j name
	col:	Common official language indicator
	cor:	Restricted official lang indicator based on narrower definition of official lang
	cnl:	Common native language index
	cal:	Common acquired language index
	csl:	Common spoken language index (native and acquired)
	lpn:	Linguistic proximity index for different native languages
	lpa:	Linguistic proximity index for different acquired languages
	lps:	Linguistic proximity index for different spoken languages (native and acquired)