How would I make a valid comparison using ARCGIS census tract population centroids within a one mile radius of an address to the results using a SQL Server geography spatial index of latitude and longitude points of centers of population within a one mile radius around the same address? When counting the census tracts with population weighted centroids from ESRI ARCGIS that are within a one mile radius around an address in San Francisco, California as compared to the US Census Bureau center of population census tract points within a one mile radius of the same address as indicated by latitude and longitude using a SQL Server geography spatial index of the points, I am computing significantly different results.