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Lecture

# GGR252H1 Lecture Notes - Distance Decay, Voronoi Diagram, Centroid

Department
Geography
Course Code
GGR252H1
Professor
Stephen Swales

Page:
of 2
Feb 14th
Thiessen polygon Textbook!!
Distance, gravity model, spatial monopoly
Not entirely sure what boundaries you use- what is it closest to?
(Constriction line); which ever line is closest to Y you should use
What if there are not other centers- jut extend the lines outwards
The test for the method-
We are looking at the supply points and the competitors; based on the
boundaries of the lines of indifference
Supply and demand- market boundary look to the appendix of text
Census track data-
A problem with the boundaries may be for the places that fall btw two lines;
lets fins the center of that location, if it falls inside the service area, you
include it; if it is outside you exclude it completely
A more... fair method- either working out the squared kms, or (a little less
accurately) you could create a fine grid square system and count how many
of the squares make up the consensus area and in the service area
The smaller the grid the better
Centroid proportion grid- to deal with partial CTS
The bi-sectors, to extend the lines till they meet other lines; build up a set of
polygons and figure out the market in each
o Service area- hospital etc-
o Locations
o Trade areas in the city/where with the city
o Which site within the market area (site selection)
Normative models
o Thiesen polygon (distance/proximity)
o Converse breakpoint method (distance and size/attractiveness)-
simple gravity model
o Huff model (distance, size and probability)- gravity model
Behavioral models
o Market penetration techniques (applebaun) costumer spotting
Relevant concepts:
o Distance decay, friction of distance
o Disincentive nature of distance (really economic)
o Location and competition (hoteling)
o Utility (distance, size, and attraction)
o Unifying/simplifying assumptions- effectiveness model
The techniques
o Construction methods
o Assumptions
o Applications
o Criticism/limitations
Draw constructions line between a center and all adjacent center
Bisect each of these construction lines (ex. measure exactly halfway along
each line
IN TEXTBOOK (chapter 5)
What should be vertices?
o Lines of indifferences
Distance is the only variable of competition- thiessen