Question for point pattern experts
On 11/02/2011, at 6:00 AM, david depew wrote:
Dear list, A brief and (hopefully) simplistic question regarding point pattern analysis. We have compiled a large, continental database of chemical burdens in a model organism. Currently, the data span 40 years and covers the entire country of Canada (including the high arctic). We have categorized the numeric data into categorical data (i.e. categorical marks) based on risk thresholds. We'd like to assess whether or not there are interesting spatial patterns ( i.e. clusters of levels of risk (high vs low)), much like a case/control approach. My question is as follows; Is there a "best" geographic projection for this approach? Currently all data are in Latitude/Longitude. My inclination is to use something along the lines of an equal area projection to maintain a reasonable representation of spatial dispersion.
This doesn't sound to me like ***point pattern*** data. It sounds like you have taken measurements of ``chemical burdens'' in a particular organism, at a number of ***chosen*** sites over a number (40) of years. Thus the observation points are deterministic, not random, and so point pattern analysis doesn't come into it. It may be the case that some sort of combination of kriging and time series or repeated measures analysis might be called for. But here I speak of that of which I know nothing. cheers, Rolf Turner