A state-year panel of contributions to United Nations peacekeeping operations, the archetype of a bounded, underdispersed participation count: most state-years contribute to no operation, and the states that contribute carry a tight count held in a narrow band by a turning-over roster. About 42% of state-years are zero, so it is also a natural example for the hurdle-CPB.
Usage
data(peacekeeping)Format
A data frame with 4,448 rows and 9 variables:
- iso3
ISO3 country code (the panel unit).
- year
Calendar year, 1990–2016.
- contributions
Number of distinct UN peacekeeping operations the state contributes personnel to in that year (the count outcome).
- democracy
Electoral-democracy index.
- lgdppc
Log GDP per capita.
- lpop
Log population.
- milper
Military personnel, thousands.
- majorpower
Major-power indicator (0/1).
- region
World region.
Source
Contribution counts aggregated from the International Peace Institute Providing for Peacekeeping database (https://www.providingforpeacekeeping.org); covariates from V-Dem and the Correlates of War National Material Capabilities data. Counts and public covariates only; prepared for illustration.
Examples
data(peacekeeping)
table(peacekeeping$contributions == 0)
#>
#> FALSE TRUE
#> 2602 1846
# \donttest{
some <- subset(peacekeeping, iso3 %in% unique(iso3)[1:40]) # forty states keep the example short
## among these forty states every major power contributes, so majorpower would
## separate the participation equation (hurdle_cpb() warns when it does)
fit <- hurdle_cpb(contributions ~ lgdppc + milper, data = some,
participation = ~ democracy + lgdppc, fe = "iso3")
fit
#> Hurdle Continuous Parameter Binomial (intensity fixed effects on 'iso3')
#> Call: hurdle_cpb(formula = contributions ~ lgdppc + milper, data = some, participation = ~democracy + lgdppc, fe = "iso3")
#> Units: 1020 (588 participate, 58%)
#>
#> Participation (logit link) -- positive coefficients raise P(Y > 0), i.e. participation:
#> (Intercept) democracy lgdppc
#> -1.4315 3.4018 -0.0112
#>
#> Intensity (zero-truncated CPB) coefficients:
#> lgdppc milper
#> 0.2740 -0.0011
#> Intensity alpha (shape): 0.6635
# }