Prediction of batch heat transfer coefficients for pseudoplastic fluids ...

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Table 5-5 and 5-6.
A measure of the significance of the difference betv-reen
tlfJO correlations is determined by using the F test
~'Ilhere
F is the ratio of the variances of the two correlations
(55). The variance is the sum of the squares of the difference
between the measured ~nd
predicted values of the dependent
variable. The significance of the F is dependent
upon the degrees of freedom -of each of the tl-JO variances ..
The number of degrees of freedom is equal to the number of
data points minus the nmnber of constants calculated from
the data. Table 5-7 lists the variances for these correlations.
In testing the significance between correlations A and
C for the anchor agitator~F
is evaluated as follows.
Correlation
Variance
Number of
Data Po.ints
Number of
Constants
Degrees
of Freedom
A
C
963,790 39
537,312 39
4
6
35
33
F35, 33 = ~632790 = 1.80
37,312
(5-6
A table of values for the F distribution ShOHS that for F
to be significant at the 80% limit for 35 and 33 degrees of
freedom,F must be greater than 1.57.. At the 90% limit F
must be greater than 1 .. 79 and at the 95% limit F must be