Page 110 - 6685

Figure 7.1 – Actual and theoretical curves

The degree of the precision composite equation is judged
by a correlation coefficient, which is determined by the formula
 log t log q   nt / log t log q   t
r  aver aver , (7.3)
 t   q oil   t
where  and  q oil   t - mean-square deviation
t

 log t log t  2
  aver , (7.4)
t
n
 log q   t log q    2
t
 q ( t)  n aver , (7.5)
oil
where log t aver and log q   t aver - the arithmetic mean of all
values of logarithms t and q oil(t).
The correlation coefficient ranges from -1 to +1. The
closer the correlation coefficient to the unit, the more accurate

110