Hello! I’m trying to get accustomed to pymc3 and bayesian models in general. In particular right now I’m trying to fit a michaelis-menten-type model to my data, with a normal variance around the deterministic model for the mean with a standard deviation of ϵ: y \sim N(\mu = \frac{x}{x+k}, \epsilo…

The problem might be coming from your noise prior, since it can give invalid negative numbers for the standard deviation of you likelihood. Try to replace it with a positive distribution like the HalfNormal or even better a Gamma and see if your problems go away.

Need help with simple asymptote model using toy data

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danchurch January 28, 2021, 10:26am 3

Perfect, thanks! Makes sense now that I think about, standard deviations can’t be negative. What is a “noise” prior?

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Need help with simple asymptote model using toy data

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