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Create state-years from state system membership data

Source: R/create_stateyears.R
create_stateyears.Rd

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. The function leans on internal data provided in the package.

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 2017 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.

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.

References

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

Author

Steven V. Miller

Examples


# CoW is default, will include years beyond 2016 (most recent CoW update)
create_stateyears()
#> # A tibble: 16,926 × 3
#>    ccode statenme                  year
#>    <dbl> <chr>                    <int>
#>  1     2 United States of America  1816
#>  2     2 United States of America  1817
#>  3     2 United States of America  1818
#>  4     2 United States of America  1819
#>  5     2 United States of America  1820
#>  6     2 United States of America  1821
#>  7     2 United States of America  1822
#>  8     2 United States of America  1823
#>  9     2 United States of America  1824
#> 10     2 United States of America  1825
#> # … with 16,916 more rows

# Gleditsch-Ward, include most recent years
create_stateyears(system="gw")
#> # A tibble: 18,463 × 3
#>    gwcode statename                 year
#>     <dbl> <chr>                    <int>
#>  1      2 United States of America  1816
#>  2      2 United States of America  1817
#>  3      2 United States of America  1818
#>  4      2 United States of America  1819
#>  5      2 United States of America  1820
#>  6      2 United States of America  1821
#>  7      2 United States of America  1822
#>  8      2 United States of America  1823
#>  9      2 United States of America  1824
#> 10      2 United States of America  1825
#> # … with 18,453 more rows

# Gleditsch-Ward, don't include most recent years
create_stateyears(system="gw", mry=FALSE)
#> # A tibble: 17,767 × 3
#>    gwcode statename                 year
#>     <dbl> <chr>                    <int>
#>  1      2 United States of America  1816
#>  2      2 United States of America  1817
#>  3      2 United States of America  1818
#>  4      2 United States of America  1819
#>  5      2 United States of America  1820
#>  6      2 United States of America  1821
#>  7      2 United States of America  1822
#>  8      2 United States of America  1823
#>  9      2 United States of America  1824
#> 10      2 United States of America  1825
#> # … with 17,757 more rows