Ferguson under sustained attack now.
Coding that led to lockdown was 'totally unreliable' and a 'buggy mess', say experts
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The code, written by Professor Neil Ferguson and his team at Imperial College London, was impossible to read, scientists claim
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“There appears to be a bug in either the creation or re-use of the network file. If we attempt two completely identical runs, only varying in that the second should use the network file produced by the first, the results are quite different,” the Edinburgh researchers wrote on the Github file.
After a discussion with one of the Github developers, a fix was later provided. This is said to be one of a number of bugs discovered within the system. The Github developers explained this by saying that the model is “stochastic”, and that “multiple runs with different seeds should be undertaken to see average behaviour”.
https://www.telegraph.co.uk/technology/2020/05/16/coding-led-lockdown-totally-unreliable-buggy-mess-say-experts/
I don't really understand the bolded part. Logically the only way I can see how the results can vary is if a) if the seed is altered b) there is a random component in the model. To my understanding a would be somewhat akin to weather model ensembles where the starting conditions are varied to account for uncertainty. Not sure about b, perhaps a random component to address uncertain patterns of human behaviour?
Apparently much of the code is very old and some has been converted from Fortran. Neither point necessarily implies a problem or shortcoming IMO.
Originally Posted by: Brian Gaze