Scale-up Suite Help
Fitting results chart
Fitting > Fitting Results > Fitting results chart
 Fitting history

The Fitting history is available in the Excel and web fitting reports after a fit has finished successfully. This contains the parameter values and SSQ (or Chi-squared) value as a function of iteration number. The SSQ should drop as the iterations proceed (indicating that the fit is improving). Once a good fit is found both the SSQ and the parameter values should level off (i.e. not change significantly with iteration). A flat section on the graph is normally due to:

 Data vs. Model chart

This chart displays the experimental data and model predictions versus time for each scenario. It allows an alternative assessment of the fitting progress. As the fit proceeds the lines (model predictions) should move towards the points (experimental data) on each scenario.

Only one scenario is plotted on the chart. To view a different scenario use the forward and back buttons (>> and <<) at the bottom right of the chart.

You can change the scale of the y-axis either by using the chart controls on the y-axis or by clicking on a series in the legend at the bottom of the chart.

 Residuals only chart

This chart displays the difference between the experimental data and model predictions versus time for each scenario. It is only available when a fit has completed.

If the fit is good, the residuals should look random. Trends in the residuals indicate that the model is not adequate to describe the data. Either the wrong type of model was used (e.g. fitting a first order reaction to data collected from a second order reaction) or more parameters are required to describe the data (either fit more parameters, or increase the complexity of the model (e.g. add another reaction).