Geography Reference
In-Depth Information
Exercise
1.
EXTENDED EXERCISE
Chi Square Analysis
Objective
Learn basic concepts of chi-square analysis and issues that influence geostatistical
analysis.
Description
The chi-square analysis is a straightforward statistical technique to evaluate the
validity of hypotheses. While it can get rather complicated for large tables, for simple
two-dimensional tables it is still a simple statistical technique. The only thing you
should bear in mind when working with chi-square analysis and geographic infor-
mation that geographic information is rarely, if ever, follows a normal distribution.
Instructions
First you need to prepare a combined map of precipitation and forested areas in
Isaland. The null hypothesis is that forested areas are more common in areas with
higher rainfall.
Here is list of the steps:
Prepare combined map
Precipitation by High/Low
Forest by Forested/Nonforested
Prepare tabulation
Prepare observed frequencies and expected frequencies matrices
Determine chi-square statistic
Calculate Yule's Q
Answer questions
You will use two equations:
Chi-square
(
ObservedFrequency ExpectedFrequency
ExpectedFrequency
−
)
2
∑
2
χ
=
Yule's Q
ad
−
+
bc
ad
bc
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