
Spatial Statistical Methods 179
R =
n
P
i=1
(x
i
−
¯
X)(y
i
−
¯
Y )
nS
x
S
y
(9.9)
where
S
x
=
s
n
P
i=1
(x
i
−
¯
X)
2
N
and S
y
=
s
n
P
i=1
(y
i
−
¯
Y )
2
N
The S
x
and S
y
are standard deviations in x and y directions respectively.
The computed value of R for any data population varies on a scale from
+1 through 0 to −1.
• R = +1 implies perfect positive association, whereby as values of one rise
they also rise of the other. The phenomena of increase in real estate rate in
a locality implies high and increased income of occupants and increase per
capita income of the locality.
• R = 0 implies no association between the phenomena or attribute under
study. For example the annual rate of rainfall over ...