
Chapter 4
PB
Measures of Dispersion
165
r
nxyxy
nx xnyy
=
−
−−
=
×−
∑∑∑∑
()()
()()()()
,,.(
2222
13 17 586 588 04 992 505 1 2272
13 676 135 454 78557 193 526 13 10
,.)( )
(,,.),,, (,
×
×−
(
)
× 331 274 5 161 984,),,−
(
)
= 0.4214
Hence, the correlation coef cient between sales and advertisement is +0.4214. This indicates that
sales and advertisement are positively correlated but the degree of correlation is not very strong.
Figure 4.34 is MS Excel out put exhibiting correlation coef cient between sales and advertise-
ment for Example 4.15.
FIGURE 4.34
Excel output
exhibiting correlation
coeffi cient
between sales and
advertisement for
Example 4.15
Example 4.16
ITC has ...