n_eff function

Effective sample size

An approximate calculation for the effective sample size for spatially autocorrelated data. Only valid for approximately normally distributed data.

Source

Griffith, Daniel A. (2005). Effective geographic sample size in the presence of spatial autocorrelation. Annals of the Association of American Geographers. Vol. 95(4): 740-760.

n_eff(n, rho)

Arguments

• n: Number of observations.
• rho: Spatial autocorrelation parameter from a simultaneous autoregressive model.

Returns

Returns effective sample size n*, a numeric value.

Details

Implements Equation 3 from Griffith (2005).

Examples

n_eff(100, 0)
n_eff(100, 0.5)
n_eff(100, 0.9)
n_eff(100, 1)

rho <- seq(0, 1, by = 0.01)
plot(rho, n_eff(100, rho),
     type = 'l',
     ylab = "Effective Sample Size")

See Also

sim_sar , aple