Locally Weighted Analysis of Spatially Aggregate Birth Data : Uncertainty Estimation and Display

The concern is the analysis and display of data that is aggregate over geographic regions (such as census divisions) for phenomena that are felt to vary smoothly in space. In Brillinger (1990b) some spatial locally weighted analyses were provided for births taking place to women aged 25 to 29 in the years 1986 and 1987 for the province of Saskatchewan at the census division level. Various results were displayed via contour plots. The present work develops these ideas further and is, in particular, concerned withi the computation and display of appropriate uncertainty levels for contour plots. A weekday effect is noted, but it does not vary appreciably with space. The approach provides an alternative to the empirical Bayes methods that have been proposed for similar problems.