MATLAB Answers


Fitting multiple dependent variables with time less than zero

Asked by Jim Bosley on 8 Jul 2019
Latest activity Commented on by Jim Bosley on 9 Jul 2019
Suppose I have a therapeutic d that modulates an endogenous substance e. I've a pd model of e (for the sake of argument, a constant synthesis rate, and a linear clearance). I've a pk model for d. I have some sort of model that has e interact and bind with d, and the bound complex has a different clearance rate than e alone. My dataset has therapeutic doses applied to subjects at time zero. But I have undosed data for t<0 - perhaps a dataset of a couple months for e leading into the dosing period. The earlier data helps me set the parameters pertaining to e.
But the fitting programs won't accept any data earlier than t=0. Is this correct? Is my workaround to bias all times so that all time values are positive, and to tell SB that the dose is delayed by this bias? Or can I tell SB to accept values of time less than zero?


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1 Answer

Answer by Arthur Goldsipe on 9 Jul 2019
 Accepted Answer

Right now, SimBiology simulations always have to start at zero. So for your problem, you'd have to adjust the data with an offset so there are no negative times.

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