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Load military expenditure data

Source: R/load_military_expenditure_data.R
load_military_expenditure_data.Rd

Loads country-year military expenditure data from one of the sources included with the package.

Usage

load_military_expenditure_data(
  start_year = 1945,
  end_year = 2019,
  dataset = c("sipri", "nmc", "barnum"),
  coding_system = c("cow", "gw")
)

Source

SIPRI: Stockholm International Peace Research Institute (2025). SIPRI Military Expenditure Database. https://www.sipri.org/databases/milex

NMC: Singer, J. David, Bremer, Stuart & Stuckey, John (1972). Capability Distribution, Uncertainty, and Major Power War, 1820-1965. National Material Capabilities v7.0. https://correlatesofwar.org/data-sets/national-material-capabilities/

Barnum: Barnum, M., Fariss, C.J., Markowitz, J.N., & Morales, G. (2025). Measuring Arms: Introducing the Global Military Spending Dataset. Journal of Conflict Resolution, 69(2-3), 540-567.

Arguments

start_year

Integer. First year to include.

end_year

Integer. Last year to include.

dataset

Character. Dataset to load:

"sipri"

SIPRI Military Expenditure Database v1.2: spending in constant (2024) USD millions (sipri_milex) and military burden as a share of GDP (sipri_milburden, a fraction, not a percentage). Coverage: 1949-2025.

"nmc"

Correlates of War National Material Capabilities v7.0 (abridged): military expenditure in thousands of current USD (nmc_milex). Coverage: 1816-2022.

"barnum"

Global Military Spending Dataset (Barnum, Fariss, Markowitz & Morales 2025): military burden (barnum_milburden, a fraction of GDP) plus latent-model expenditure estimates on two unit bases (barnum_sipri, barnum_nmc; see Details). Coverage: 1816-2019.

coding_system

Character. Country coding system: "cow" or "gw".

Value

A country-year data frame. Columns differ by dataset:

sipri: cow/gw, year, sipri_milex, sipri_milburden.

nmc: cow/gw, year, nmc_milex.

barnum: cow/gw, year, barnum_milburden, barnum_sipri, barnum_nmc.

Details

NMC's -9 missing-data sentinel is recoded to NA in nmc_milex.

The SIPRI workbook lists a small number of rows (e.g. "Africa", "NATO") that are regional or organizational aggregates rather than countries; these have no matching COW/Gleditsch-Ward code and are dropped when countrycode::countrycode() returns NA.

Barnum et al.'s replication files contain one row per country-year for each of 24 underlying source indicators (SIPRI, WMEAT, NCD, IISS, and others), each already reported in its own original currency/unit. Unlike Fariss et al. (2022)'s GDP and population estimates, the paper does not publish a single combined "latent" value on a real monetary scale: "the average by itself does not have a real or direct monetary unit" (p. 550). Instead, barnum_sipri and barnum_nmc are the model's posterior estimate of two specific indicators (the "milex_con_2022_sipri" and "milex_con_2017_nmc" series respectively), which extends each one's coverage back to 1816 using information from all 24 sources, still expressed in that indicator's own original units. barnum_milburden is milexgdp from Barnum et al.'s separate military-burden estimates file, which is unit-free and so is published directly.

Both "_con_" indicators are in constant (inflation-adjusted) dollars, unlike nmc_milex from dataset = "nmc", which NMC documents in current-year dollars. barnum_nmc is therefore not directly comparable to nmc_milex: their ratio varies smoothly over time (e.g. around 2.4 for the United States in 1990, falling toward 1 by the mid-2010s), which reflects cumulative inflation adjustment rather than disagreement between the two sources.

References

Singer, J. D., Bremer, S., & Stuckey, J. (1972). Capability distribution, uncertainty, and major power war, 1820-1965. In B. Russett (Ed.), Peace, War, and Numbers (pp. 19-48). Sage.

Singer, J. D. (1988). Reconstructing the Correlates of War dataset on material capabilities of states, 1816-1985. International Interactions, 14, 115-132.

Stockholm International Peace Research Institute. (2025). SIPRI Military Expenditure Database. doi:10.55163/CQGC9685

Barnum, M., Fariss, C. J., Markowitz, J. N., & Morales, G. (2025). Measuring arms: Introducing the Global Military Spending Dataset. Journal of Conflict Resolution, 69(2-3), 540-567. doi:10.1177/00220027241232964

Examples

milex_sipri <- load_military_expenditure_data(1990, 2015, dataset = "sipri", coding_system = "cow")

milex_nmc <- load_military_expenditure_data(1900, 2015, dataset = "nmc", coding_system = "cow")