Best practices for chemical data curation and QSAR model ...
Best practices for chemical data curation and QSAR model ...
Best practices for chemical data curation and QSAR model ...
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HOW TO DEFINE A PREDICTIVE <strong>QSAR</strong> MODEL<br />
10<br />
8<br />
y = 0.3154x + 3.4908<br />
R 2 = 0.9778<br />
10<br />
8<br />
y = 3.1007x - 10.715<br />
R 2 = 0.9778<br />
9<br />
y = 1.2458x - 1.8812<br />
R 2 = 0.8604<br />
Observed<br />
6<br />
4<br />
2<br />
y = 0.9383x<br />
R 2 0 = -3.3825<br />
Predicted<br />
6<br />
4<br />
2<br />
y = 1.0023x<br />
R 2 0 = 0.5238<br />
Observed<br />
7<br />
5<br />
y = 0.9796x<br />
R 2 0 = 0.8209<br />
0<br />
0 2 4 6 8 10<br />
Predicted<br />
0<br />
0 2 4 6 8 10<br />
Observed<br />
3<br />
3 5 7 9<br />
Predicted<br />
a'<br />
=<br />
~ y r = a'<br />
y + b '<br />
a =<br />
y r 0<br />
= ky ~<br />
k<br />
=<br />
Regression<br />
( y )( ~ ~<br />
i<br />
− y yi<br />
− y )<br />
( y y)( ~ 2<br />
( y y ~<br />
i<br />
−i<br />
−<br />
y )<br />
~ )<br />
2<br />
( ~<br />
i<br />
−<br />
y − y<br />
∑<br />
∑<br />
~ ∑<br />
i<br />
b ' = y − a'<br />
y<br />
b = y − ay ~<br />
∑<br />
∑<br />
y ~ y<br />
i i<br />
~ 2<br />
yi<br />
Correlation coefficient<br />
R =<br />
∑<br />
∑ (<br />
q<br />
k<br />
2<br />
( y − )( ~ − ~<br />
i<br />
y yi<br />
y )<br />
2<br />
y − y)<br />
( ~ y − ~ y )<br />
i<br />
∑<br />
> 0.5; R<br />
or<br />
k<br />
'<br />
i<br />
2<br />
~ y r 0<br />
= k'<br />
y<br />
k'<br />
=<br />
CRITERIA<br />
2<br />
><br />
≈ 1.0; R<br />
Regression through<br />
the origin<br />
0.6;<br />
2<br />
0<br />
or<br />
∑<br />
∑<br />
R<br />
y ~ y<br />
i i<br />
2<br />
i<br />
y<br />
'2<br />
0<br />
≈<br />
R<br />
2<br />
Coefficients of determination<br />
R<br />
2<br />
0<br />
R'<br />
2<br />
0<br />
= 1 −<br />
= 1−<br />
∑<br />
∑<br />
∑<br />
∑<br />
( ~ r0<br />
y y )<br />
~ )<br />
2<br />
( ~<br />
i<br />
−<br />
i<br />
y − y<br />
( y<br />
i<br />
( y<br />
i<br />
− ~ y<br />
i<br />
r<br />
i<br />
0<br />
)<br />
− y)<br />
2<br />
2<br />
2