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17  35 21 32
X  3aver   26 . 25
4

Comparing average values for minimum and maximum
levels of each factor, we can see, that the difference between
these levels for the third factor X 3 is the smallest, which means
it does not influence the process significantly, and it can be
ignored.
To determine the main factors, which influence the
process, we use associative analysis, in which the relationship
of any two factors between each other is determined by
coefficient of association.
Task 4.8
According to industrial data, it is necessary to establish
whether there is a relationship of porosity, permeability and
coefficient of oil extraction for 15 fields. All information about
the porosity, permeability and coefficient of oil extraction is
divided into two random groups:
m > 10 % m < 10 %
-3
2
-3
k > 5∙10 мкм k < 5∙10 мкм 2
η > 0,35 η < 0,35
Table for analyzing the impact of porosity on coefficient
of oil extraction:
m, % η > 0,35 η < 0,35 Sum up
m > 10 7 (а) 0 (b) 7 (a+b)
m < 10 2 (с) 6 (d) 8 (c+d)
Sum up 9 (a+c) 6 (b+d) 15 (N)
Coefficient of association is determined by the formula:
ad  bc
  (4.22)
(a  b )(c  d )(a  c )(b  ) d
,
where a , b , c , d — symbols of number of fields;
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