ai-geostats  

AI-GEOSTATS: "Naive" question on lat-long conventions

Mark Coleman
Thu, 15 Apr 2004 07:44:12 -0700

Greetings,

I apologize in advance for what must be a rather naive question, but I am new to the field of spatial statistics. In the course of learning and testing various estimation methods with test data sets, I have a couple of questions regarding conventions regarding lat-long coordinates. In particular, I have been using a small test data set provided by Anselin on crime data in Columbus OH. Each sample point includes a lat-long coordinate. The data set can be found at http://www.spatial-econometrics.com/data/

As an example, the first point in this data set shows latitude=35.62, longitude=42.38. Yet when I check the coordinates of a random point in Columbus OH (not in the dataset), I find coordinates in the range of Lat=40.x, Long= -82.y. I use the points in the Anselin data set to calculate a spatial distance matrix using Delaunay Triangulization. I wanted to be sure that I understand what the conventions are when encoding lat-long coordinates. In the end, I need to understand this so I can calculate the distance between two points based on their lat-long coordinates.

Thanks,

Mark


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