Table 1 Percent of length reduction for 95% CI for rate ratios, from non-spatial method to spatial method with varying spatial autocorrelation scale (measured by range in semivariogram) and strength (measured by partial sill to sill proportion in semivariogram)

Strength of spatial autocorrelation

 0.1 (weak)

(0, 0.004, 0.095)

0.48

(0.005, 0.039, 0.098)

1.7

(0.029, 0.067, 0.099)

2.7

 0.5 (moderate)

(0, 0.02, 0.47)

2.4

(0.027, 0.19, 0.49)

9.2

(0.14, 0.33, 0.50)

14.6

 0.9 (strong)

(0, 0.036, 0.85)

4.5

(0.048, 0.35, 0.89)

17.7

(0.26, 0.60, 0.89)

29.3