A data set consisting of case and control locations is to be analyzed for evidence that the case pattern is representative of a contagious disease process.

Questions:

1. Assuming that the data set contained no time of diagnosis, but was a "snapshot" of the disease from an early point in the epidemic for the area, you might hypothesize strong spatial clustering in the case locations. Can you construct a gamma statistic that would show high values to indicate strong clustering in this case, based on the spatial pattern of nearest neighbors?
2. Suppose now that you introduce time of diagnosis into the data set. What would be your hypothesized distribution of spatial/temporal pattern? What real-life factors would play a role in either accentuating or obscuring your hypothesized pattern?