Data Sources

In 1992 and 1993, a series of interviews of boat owners was conducted in the Sarasota Bay area as part of a waterway management project (Antonini and Box, 1996). Included with the boater interviews was information about how often the boaters took their boats out, what kinds of boating activities they most commonly did, preferred destinations, weather conditions, and other information that could be useful for understanding the nature of boat traffic in that area. Since this data set was a representative sample of boaters in Sarasota Bay, it was assumed that boat traffic information inferred from this data set could be safely extrapolated to the boating population at large.

From the information gathered in these interviews, it was readily apparent that boaters are a highly varied population, and that there was an extremely high variability in kinds of boats, kinds of behaviors, and kinds of trips. It was apparent from even a cursory look at the data that at least two kinds of boat trips would have to be considered: traffic that followed established routes (channels), analogous to automobile traffic, and traffic that moved through open areas. Boats from one kind of traffic would be interacting in a common system with the boats that are not in distinct channels, and in fact individual boats could change from one kind of trip to another at any time during its trip.

From the size of the data set, it was found that attempts to make global inferences characterizing the population were confounded by a very high variance in results. That high variance could be attributed either to the sample size being too small to adequately capture global trends, or else that the population in question is inherently diverse and defies description by simple statistics. Whichever reason proves to be true, the data set does not support modeling of boat traffic through global inferences, but is quite adequate for modeling probable behavior of individual boats.