igo_dyadic: Extract joint membership for a pair of countries across IGOs

In igoR: Access the Intergovernmental Organizations Database

Extract joint membership for a pair of countries across IGOs

Description

Create a dyadic version of the data. The unit of observation is a country dyad. The result summarizes joint memberships across IGOs over time.

Usage

igo_dyadic(country1, country2, year = 1816:2014, ioname = NULL)

Arguments

country1, country2	State or vector of states to compare. Values can be any valid state name or code as specified in states2016.
year	Year to assess, as an integer or vector of years.
ioname	Optional. ioname or vector of ioname corresponding to the IGOs to assess. If NULL (the default), all IGOs will be extracted. See codes in igo_search().

Details

This function tries to replicate the information contained in the original file distributed by The Correlates of War Project (dyadic_format3.dta). That file is not included in this package due to its size.

The result is a data.frame with one row for each common year selected via country1, country2 and year.

An additional column, dyadid, computed as (1000 * ccode1) + ccode2, is provided to identify relationships.

For each IGO selected via ioname, or all IGOs if the default option is used, a column using lowercase ioname as an identifier is provided with the following coding system:

Category	Numerical Value
No Joint Membership	0
Joint Full Membership	1
Missing data	-9
State Not System Member	-1

See the igo_recode_dyadic() section for an easy way to recode the numerical values into factors.

If one state in an IGO is a full member but the other is an associate member or observer, that IGO is not coded as a joint membership.

Value

A coded data.frame with years and country dyads as rows and selected IGOs as columns. See Details.

Differences from the original data set

Some results from this function differ from the original data set for some IGOs regarding "Missing data" (-9) and "State Not System Member" (-1). However, it is not clear how to fully replicate those values.

See Codebook Version 3 IGO Data.

Source

Codebook Version 3 IGO Data for full reference.

References

Pevehouse, J. C., Nordstrom, T., McManus, R. W., & Jamison, A. S. (2020). Tracking organizations in the world: The Correlates of War IGO Version 3.0 data sets. Journal of Peace Research, 57(3), 492–503. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1177/0022343319881175")}.

See Also

state_year_format3, states2016, igo_search().

Examples

usa_esp <- igo_dyadic("USA", "Spain")
nrow(usa_esp)
ncol(usa_esp)

dplyr::tibble(usa_esp)

# Use custom arguments.
custom <- igo_dyadic(
  country1 = c("France", "Germany"), country2 = c("Sweden", "Austria"),
  year = 1992:1993, ioname = "EU"
)

dplyr::glimpse(custom)

igoR documentation built on May 23, 2026, 5:08 p.m.