**Quality of Fit and Predictive Ability of a continuous QSAR Model**

According to A. Tropsha et al. (QSAR Comb. Sci. 22 (2003) 69-77 & Mol. Inf. 2010, 29, 476-488) the following statistical criteria must be satisfied by a predictive model:

1. R^2 >0.6

2. Rcvext^2 >0.5

3. (R^2 - R0^2)/R^2 < 0.1

4. (R^2 - R'0^2)/R^2 < 0.1

5. abs(R0^2 - R'0^2) < 0.3

6. 0.85 ≤ k ≤ 1.15

7. 0.85 ≤ k' ≤ 1.15

where:

R^2 Correlation coefficient between the predicted and observed activities

Rcvext^2 External cross validation

R0^2 Coefficient of determination: predicted versus observed activities

R'0^2 Coefficient of determination: observed versus predicted activities

k = slope: predicted versus observed activities regression lines through the origin

k’= slope: observed versus predicted activities regression lines through the origin

If this node is useful to you, please cite the following papers:

Melagraki*, G., Afantitis*, A. “Enalos KNIME nodes: Exploring corrosion inhibition of steel in acidic medium” (2013) Chemometrics and Intelligent Laboratory Systems, 123, pp. 9-14. (link)

Georgia Melagraki*, Antreas Afantitis*, Enalos InSilicoNano Platform: An online decision support tool for the design and virtual screening of nanoparticles RSC Advances 2014, 4, 50713-50725 2014 (link)

Melagraki Georgia*; Afantitis Antreas* A Risk Assessment Tool for the Virtual Screening of Metal Oxide Nanoparticles through Enalos InSilicoNano Platform Current Topics in Medicinal Chemistry, Volume 15, Number 18, September 2015, pp. 1827-1836(10) 2015 (link)

E. Vrontaki, G. Melagraki*, T. Mavromoustakos, A. Afantitis*. Searching for Anthranilic Αcid-Βased Thumb Pocket 2 HCV NS5B Polymerase Inhibitors through a Combination of Molecular Docking, 3D-QSAR and Virtual Screening Journal of Enzyme Inhibition and Medicinal Chemistry DOI:10.3109/14756366.2014.1003925 (link)

**KNIME Node Options: **

**Input Ports**

0 Values for the dependent variable, predicted by the model (ypred)

1 Values for the dependent variable for the test set (yexp)

2 Values for the dependent variable for the training set (ytr)

**Output Ports **0 Quality of Fit and Predictive Ability Statistics of a continuous QSAR Model