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Spatial Analysis
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What is
Clustering
?
Clustering algorithms divides a
dataset
into natural groups. Instances in the same cluster are
similar
to each other, they share
certain properties
.
Cluster analysis is used to
reduce
data (
dimension
) to a number of
multivariate
classes
.
Name and explain
approaches of clustering
.
Partitioning
: divide the data into a given number of clusters. (it uses k-means)
Hierarchical
: create a tree based on the similiraties/ distance of items.
Density-based
: find continguous areas with high density.
Grid-based
: divide the data space into grid cells.
what is the pupose of
Clustering by Partitioning
?
We try to make properties as
similar
as possible
within
groups and as
different
as possible
between
groups.
What are
Partitioning Methods
?
K-medoids
: use the
centermost
cluster member instead of the mean.
EM
: define the cluster by a
probability distribution
instead of a centroid.
Guaranteed to find a local optimum.
Not globally optimal clustering.
Tend to find circular clusters.
What is the disadvantage of
Hierarchical Clustering
?
You have to use your
common sense
and your
skill
to do the clustering.
Diagram
of Hierarchical Clustering.
What is Density-based clustering good for?
For finding
non-spherical
clusters.
Clusters do not necessarily cover
all
points.
Explain
Grid-based
clustering.
Goal
: find areas with high
point
desity.
divide the space to grid cells.
compute the density of points in each cell.
use the
high-density cells
to define clusters.
more effective than density-based clustering.
Spatio-temporal movement at a macro sacle?
Time is continuous.
Spatio-temporal movement at a micro sacle?
What is Tourism Market Segmentation?
A process of dividing a market into
homogeneous subgroups
. Tourists in the same group are similar to each other, and different from other groups.
What are the
objectives
of market segmentation?
Identifying and
characterising
groups of tourists.
Focusing
advertising
efforts for greater impacts.
Identifying likely
targerts
for new tourist products.
Improving
existing
products or services.
Looking for
new product services
.
Assessing the impact of a
competitor's new offering
.
Establishing a
better
tourst attraction image
.
What are the
advantages
of EM clustering algorithm
?
Primarily
catergorical
variables.
Computing the
number
of clusters.
Tending to be a
samll number
of significant clusters and a number of othes that are
not interesting
.
Each tourist is assigned into a certain cluster with
certain probability
, which govern the set of attribute values of observations in the cluster.
Author:
meh.pira
ID:
90162
Card Set:
Spatial Analysis
Updated:
2011-06-11 15:08:12
Tags:
SA
Folders:
Description:
SA 10
Show Answers:
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