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ON THE EFFECTS OF CIRCULAR BOLT PATTERNS ON THE ...

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of the dependent variable predicted from the best fit equation is x i , for any particular set of values,<br />

'<br />

li<br />

'<br />

2i<br />

'<br />

3i<br />

'<br />

X , X , X ,..., X ni , while it is measured (or directly determined) that the value isx. i Deviation of the<br />

predicted value from the measured value is given by:<br />

'<br />

i<br />

'<br />

'<br />

' '<br />

C C x C x C x<br />

xi x xi<br />

<br />

... n ni<br />

(5.7)<br />

0<br />

1 1i<br />

The sum of the squares,S for m number of data is given by:<br />

S<br />

<br />

m<br />

<br />

i1<br />

' 2<br />

xx i<br />

i<br />

2<br />

2i<br />

' (5.8)<br />

'<br />

The unknown coefficients C 0 , C1,<br />

C2,...,<br />

Cn<br />

are determined by minimizing the quality S with respect<br />

to each coefficient; in other words, by setting it equal to zero, as shown below.<br />

S<br />

C<br />

'<br />

0<br />

S<br />

<br />

C<br />

1<br />

S<br />

<br />

C<br />

This will result in 1<br />

2<br />

S<br />

... <br />

C<br />

n<br />

0<br />

95<br />

(5.9)<br />

n linear simultaneous equations from which the coefficients C 0 , C1,<br />

C2,...,<br />

Cn<br />

can be determined. To determine C , the anti-logarithm of 0<br />

0 C must be found.<br />

A “goodness of fit” of the prediction equation is a comparison of S, the sum of the squares, and the<br />

deviations for the constant term C0 above. The constant term model is:<br />

C0<br />

'<br />

S (5.10)<br />

and the sum of the squares of this model can be written as<br />

S<br />

0<br />

<br />

m<br />

<br />

i1<br />

in which<br />

' ' 2<br />

xix regression” and the ratio<br />

also be written:<br />

2<br />

R 1 <br />

0<br />

(5.11)<br />

'<br />

x 0 is the mean. The difference between S 0 and S is called as the “sum of squares due to<br />

0<br />

S <br />

S 0 2<br />

is called as the “coefficient of multiple determination,” R which can<br />

S<br />

0<br />

S<br />

(5.12)<br />

S<br />

'

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