Figure 7

LISA maps of STDRATES and SEBRATES at the Census Sub-division spatial scale. The map on the left shows the four types of significant spatial association observed for the standardized unsmoothed rates (STDRATES). The four types are: (i) high-high (high rate in an area surrounded by high values of the weighted average rate of the neighboring areas), (ii) low-low (low rate in an area surrounded by low values of the weighted average rate of the neighboring areas), (iii) high-low (high rate in an area surrounded by low values of the weighted average rate of the neighboring areas), and (iv) low-high (low rate in an area surrounded by high values of the weighted average rate of the neighboring areas). The map on the right shows the distribution of the above mentioned four types of spatial association observed for the spatial empirical Bayesian smoothed rates (SEBRATES). In both maps the areas shaded in red had significant positive spatial autocorrelation while those shaded in blue had significant negative spatial autocorrelation of giardiasis rates. There was stronger spatial association on the map on the right (i.e. for spatial empirical Bayesian smoothed rates). This suggests that the smoothed rates should only be used for visual comparison of spatial patterns and not for statistical analyses since the smoothing may lead to some artefactual effects on the tests for spatial autocorrelation of the rates.