Is the cross-country distribution actually narrowing? Reports the dispersion
of a (positive) indicator across countries for every year of a panel –
falling dispersion is sigma convergence. The natural companion to
beta_convergence(): beta convergence is necessary but not sufficient for
sigma convergence.
Usage
sigma_convergence(data, value, measure = c("sd_log", "cv"))
Arguments
- data
A panel with iso3c and year.
- value
The value column (unquoted).
- measure
"sd_log" (default; standard deviation of log values, the
standard choice) or "cv" (coefficient of variation).
Value
A tibble with one row per year: year, n (countries with
positive values) and sigma.
Examples
df <- data.frame(
iso3c = rep(c("A", "B", "C"), 2),
year = rep(c(2000L, 2010L), each = 3),
gdp = c(1, 10, 100, 2, 11, 60) # dispersion falls
)
sigma_convergence(df, gdp)
#> # A tibble: 2 × 3
#> year n sigma
#> <int> <int> <dbl>
#> 1 2000 3 2.30
#> 2 2010 3 1.70
