"Interrupted"

This checklist is for when the nonlinear regression was not able to finish, but rather reported "Interrupted" at the top of the results. View other checklists if your curve fit ended with a different completion code: Completed, Bad initial values, Not converged, Ambiguous Hit Constraint, Don't fit, Too few points, Perfect Fit or Impossible weights.

What does 'interrupted' mean?

Prism reports 'interrupted' in two situations:

•	Nonlinear regression takes more iterations than the maximum entered on the diagnostics tab (the default is 500).

•	The fit was slow, and you clicked "Interrupt" on the progress dialog.

Checklist

If the maximum number of iterations was set to a low value, set it to a higher value and try again. If you have lots of data points and lots of parameters, nonlinear regression can sometimes require hundreds of iterations.

If the maximum number of iterations was already set to a high value, you can try a still higher value, but most likely Prism is still not going to be able to find a best-fit curve. Things to check:

Did you enter the right model?

Does the curve defined by your initial values come near your data? Check the option on the diagnostics tab to plot that curve.

If you entered constraints, were they entered correctly?

If you didn't enter any constraints, consider whether you can constrain one or more parameters to a constant value? For example, in a dose-response curve can you constrain the bottom plateau to be zero?

Can you share a parameter over all the data sets (global fitting)?