12.02.02 1 Non-linear Regression Analysis with Fitter Software Application Alexey Pomerantsev Semenov Institute of Chemical Physics Russian Chemometrics Society
12.02.02 2 Agenda Introduction TGA Example NLR Basics Multicollinearity Prediction Testing Bayesian Estimation Conclusions
12.02.02 3 1. Introduction
12.02.02 4 Linear and Non-linear Regressions Close relatives? 2
12.02.02 5 2. Thermo Gravimetric Analysis Example Let’s see it!
12.02.02 6 TGA Experiment and Data TGA Experiment TGA Data
12.02.02 7 TGA Example Variables Small size problem!
12.02.02 8 Plasticizer Evaporation Model Diffusion is not relevant!
12.02.02 9 Fitter Worksheet for TGA Example
12.02.02 10 Service Life Prediction by TGA Data
12.02.02 11 3. NLR Basics
12.02.02 12 Data and Errors Weight is an effective instrument!
12.02.02 13 Model f(x,a) Presentation at worksheet Rather complex model!
12.02.02 14 Data & Model Prepared for Fitter Apply Fitter!
12.02.02 15 Objective Function Q(a) Parameter estimates Weighted variance estimate Objective function Q is a sum of squares and may be more…
12.02.02 16 Very Important Matrix A Matrix A is the cause of troubles..
12.02.02 17 Quality of Estimation Matrix A is the measure of quality!
12.02.02 18 Search by Gradient Method Matrix A is the key to search!
12.02.02 19 4. Multicollinearity
12.02.02 20 Multicollinearity: View Multicollinearity is degradation of matrix A Objective function Q(a) 1 N(A) = 2 4 5 6 7
12.02.02 21 Multicollinearity: Source
12.02.02 22 Data & Model Preprocessing ((a + b) + c) + d a + (b + (c + d)) as 1+10 –20 = 1
12.02.02 23 Example: The Arrhenius Law
12.02.02 24 Derivative Calculation and Precision 1) Numerical calculation of difference derivatives
12.02.02 25 5. Prediction
12.02.02 26 Reliable Prediction Forecast should include uncertainties!
12.02.02 27 Nonlinearity and Simulation Non-linear models call for special methods of reliable prediction!
12.02.02 28 Prediction: Example Accelerated aging tests Upper confidence limits Model of rubber aging
12.02.02 29 6. Testing
12.02.02 30 Hypotheses Testing Test statistics x is compared with critical value t (a) Test don’t prove a model! It just shows that the hypothesis is accepted or rejected!
12.02.02 31 Lack-of-Fit and Variances Tests These hypotheses are based on variances and they can’t be tested without replicas! Lack-of-Fit is a wily test!
12.02.02 32 Outlier and Series Tests These hypotheses are based on residuals and they can be tested without replicas Series test is very sensitive!
12.02.02 33 7. Bayesian Estimation
12.02.02 34 Bayesian Estimation How to eat away an elephant? Slice by slice!
12.02.02 35 Posterior and Prior Information. Type I The same error in each portion of data!
12.02.02 36 Posterior and Prior Information. Type II Different errors in each portion of data!
12.02.02 37 8. Conclusions Mysterious Nature LR Model NLR Model Thank you!