create_stateyears: Create state-years from state system membership data

In svmiller/peacesciencer: Tools and Data for Quantitative Peace Science Research

Create state-years from state system membership data

Description

create_stateyears() allows you to generate state-year data from either the Correlates of War (CoW) state system membership data or the Gleditsch-Ward (gw) system membership data.

Usage

create_stateyears(system = "cow", mry = TRUE, subset_years)

Arguments

system	a character specifying whether the user wants Correlates of War state-years ("cow") or Gleditsch-Ward ("gw") state-years. Correlates of War is the default.
mry	optional, defaults to TRUE. If TRUE, the function extends the script beyond the most recent system membership updates to include observation to the most recently concluded calendar year. For example, the Gleditsch-Ward data extend to the end of 2017. When mry == TRUE, the function returns more recent years (e.g. 2018, 2019) under the assumption that states alive at the end of 2016 or 2020 are still alive today. Use with some care.
subset_years	and optional character vector for subsetting the years returned to just some temporal domain of interest to the user. For example, c(1816:1820) would subset the data to just all state-years in 1816, 1817, 1818, 1819, and 1820. Be advised that it's easiest to subset the data after the full universe of state-year data have been created. This means you could, if you choose, effectively overwrite mry = TRUE with this argument since the mry argument is applied at the expansion of the state system data into state-year data.

Details

The function leans on data made available in the isard package.

Value

create_stateyears() takes state system membership data provided by either Correlates of War or Gleditsch-Ward and returns a simple state-year data frame. The Gleditsch-Ward state-years also include an indicator for whether the state is a microstate.

Author(s)

Steven V. Miller

References

Miller, Steven V. 2019. “Create Country-Year and (Non)-Directed Dyad-Year Data With Just a Few Lines in R” https://svmiller.com/blog/2019/01/create-country-year-dyad-year-from-country-data/

Examples

# CoW is default, will include years beyond 2016 (most recent CoW update)
create_stateyears()

# Gleditsch-Ward, include most recent years
create_stateyears(system="gw")

svmiller/peacesciencer documentation built on July 16, 2025, 7:01 p.m.