Create state-years from state system membership data — create

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.

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

Arguments

system

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.

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.

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: 16,731 x 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 16,721 more rows

# Gleditsch-Ward, include most recent years
create_stateyears(system="gw")
#> # A tibble: 18,289 x 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 18,279 more rows

# Gleditsch-Ward, don't include most recent years
create_stateyears(system="gw", mry=FALSE)
#> # A tibble: 17,767 x 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