10 ms·

Neil Ferguson's Imperial model could be the most devastating software mistake

35 points by JesseJon 6y ago

gargron 6y ago
Paywall?
- jjgreen 6y ago
  Loads OK with NoScript ¯\_(ツ)_/¯
eesmith 6y ago
Some previous discussion (9 comments) at https://news.ycombinator.com/item?id=23203853 https://news.ycombinator.com/item?id=23203853 Related commentary about another Telegraph article along the same lines (6 comments) at https://news.ycombinator.com/item?id=23208113 https://news.ycombinator.com/item?id=23208113 . This has had a lot of attention on HN recently: https://news.ycombinator.com/item?id=23139508 https://news.ycombinator.com/item?id=23139508 , https://news.ycombinator.com/item?id=23099499 https://news.ycombinator.com/item?id=23099499, https://news.ycombinator.com/item?id=23101077 https://news.ycombinator.com/item?id=23101077 as examples with comments.
cm2187 6y ago
The top comments from the initial discussion when the model appeared didn't age well: https://news.ycombinator.com/item?id=22637008 https://news.ycombinator.com/item?id=22637008
- rrss 6y ago
  This article is not very substantive, so: what's actually wrong with the model (in terms of predictions), and what actions should the UK government have taken instead? For the U.S., the Imperial College team predicted 2.6M deaths if nobody did anything, 474k deaths if full suppression measures were put in place at 1.6 deaths / 100k population / week, and 84k deaths in the U.S. if full suppression measures were put in place at 0.2 deaths / 100k population / week. (from https://www.imperial.ac.uk/mrc-global-infectious-disease-analysis/covid-19/report-12-global-impact-covid-19/ https://www.imperial.ac.uk/mrc-global-infectious-disease-ana...). A range of 84k to 474k deaths seems pretty reasonable given the U.S. is at something like 90k deaths today.
  - blastonico 6y ago
    A range of 84k to 474k seems reasonable? Man, I should have chosen another career area.
    - rrss 6y ago
      Yeah, reasonable, as in: the united states put full suppression measures in place piecemeal sometime between 0.2 and 1.6 deaths / 100k / week (depending on jurisdiction), and the actual number of deaths is trending to end up between the point estimate for putting measures in place at 0.2 deaths / 100k / week and the point estimate for putting measures in place at 1.6 deaths / 100k / week.
AJRF 6y ago
I was really surprised to hear that John Carmack and Github engineers were brought it to clean the code up - after - the government based some of its choices to go in to lockdown. I know more and more of us are getting sucked into the 'tinfoil hat zone' with increasing rapidity thanks to the internet - and you could competently argue I'm going there with this - but that sounds like it was done to maybe downplay fears and the fallout we've seen over the past few weeks around this code and its outsized impact on our current position. It was a 50k LoC monstrosity at one point - in a single file. Neil Ferguson was put in the spotlight as the "source of truth" by the UK media - I get that its more nuanced and I hope the UK government wouldn't have based its decisions to lockdown on this, and they instead took a wide range of data points - but the media pounced on Neils model being the thing that scared Johnson shitless into rolling back the idea of herd immunity. So then people wanted to see the model, and saw it turned out to be horrific in its quality, its lack of testing, and its potentiality to contain mistakes (which it did - given Neil rolled back his predictions after a while) I think that probably spooked some high profile people into action. The whole thing is weird and Neils reputation is in tatters in the media over the way this thing has played out (as well as for some of his extra-curricular activities).
- rrss 6y ago
  > which it did - given Neil rolled back his predictions after a while Can you please source this? Sorry to have to ask, but last time someone said this it turned out they were comparing predictions in dissimilar scenarios from two different countries.
- Yoric 6y ago
  > Neil Ferguson was put in the spotlight as the "source of truth" by the UK media - I get that its more nuanced and I hope the UK government wouldn't have based its decisions to lockdown on this, and they instead took a wide range of data points - but the media pounced on Neils model being the thing that scared Johnson shitless into rolling back the idea of herd immunity. Yeah, I read different stories in different newspapers. Such as the rest of the EU, er, politely insisting that the UK was doing something really stupid and needed to change course immediately, not giving Johnson much of a choice. I strongly doubt that the entire EU had based their models on those of a single UK research team.
cnorthwood 6y ago
As far as I can get the argument boils down to "the model is stochastic", "Fortran is old" and "the code is spaghetti". Of which the first one is deliberate, the second one I don't see as a problem, and the last one is definitely a risk factor, but is far from a guarantee that the model is flawed or broken.
- Yoric 6y ago
  That's also my understanding. I would also be strongly surprised if this was the only study used by, well, most of the world to determine their policies. Even if one study isn't as well-{architected, tested} as a computer engineer would hope (hint: they never are), the fact that pretty much all models/studies lead to the same overall conclusion is quite encouraging.
- s9w 6y ago
  The code that was released already heavily altered for a month as I recall. And in that state it contained several severe flaws. If you look at it it's painfully obvious that it's just not fit for anything critical. I applaud that they published it. But I also want the consequences: No funding for this quality of work. Also do the opposite of what they say.
- jeffbarg 6y ago
  My understanding of the frustration is that while the model is deliberately stochastic, there was still unexplained non-determinism in the model that had to be fixed (and still persists). If the randomness isn't fully explained by pre-determined seeds, I'd call that an error.
  - tripletao 6y ago
    Here's the GitHub issue: https://github.com/mrc-ide/covid-sim/issues/116 https://github.com/mrc-ide/covid-sim/issues/116 The discussion isn't terribly clear to me. Is this non-determinism in which random number gets used where, like if you seed an RNG once and then use it from multiple threads that get scheduled in varying order? That wouldn't be good, but the model would still be performing as intended, just with no way to make it deterministic for testing. Or is it some other kind of non-determinism? I'm not sure anyone knows, which indeed isn't totally comforting. I'm not sure the "bug uncertainty" is any bigger than all the existing known uncertainty about the assumptions that go in to his (or any such) model, though.
hprotagonist 6y ago
are we whining about only having functional tests still, or have actual bugs been demonstrated that substantively affect model output? If so, what's the link to those issues on their github? the last time this came up it was firmly in the former camp, and was pretty small beer as a result.
deleted 6y ago
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deleted 6y ago
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calebm 6y ago
Perhaps this should serve as a good case study for why reproducible research is so important.
lerno 6y ago
Yeah you should totally do like Sweden where dead remains at a constant high level and where reduction to a low number of cases per day is very very far away. This “almost lockdown” strategy is almost equally hurtful for the economy but will need to be sustained for much longer.

35 points by JesseJon 6y ago

gargron 6y ago

Paywall?

jjgreen 6y ago
Loads OK with NoScript ¯\_(ツ)_/¯

eesmith 6y ago

Some previous discussion (9 comments) at https://news.ycombinator.com/item?id=23203853 https://news.ycombinator.com/item?id=23203853 Related commentary about another Telegraph article along the same lines (6 comments) at https://news.ycombinator.com/item?id=23208113 https://news.ycombinator.com/item?id=23208113 . This has had a lot of attention on HN recently: https://news.ycombinator.com/item?id=23139508 https://news.ycombinator.com/item?id=23139508 , https://news.ycombinator.com/item?id=23099499 https://news.ycombinator.com/item?id=23099499, https://news.ycombinator.com/item?id=23101077 https://news.ycombinator.com/item?id=23101077 as examples with comments.

cm2187 6y ago

The top comments from the initial discussion when the model appeared didn't age well: https://news.ycombinator.com/item?id=22637008 https://news.ycombinator.com/item?id=22637008

rrss 6y ago
This article is not very substantive, so: what's actually wrong with the model (in terms of predictions), and what actions should the UK government have taken instead? For the U.S., the Imperial College team predicted 2.6M deaths if nobody did anything, 474k deaths if full suppression measures were put in place at 1.6 deaths / 100k population / week, and 84k deaths in the U.S. if full suppression measures were put in place at 0.2 deaths / 100k population / week. (from https://www.imperial.ac.uk/mrc-global-infectious-disease-analysis/covid-19/report-12-global-impact-covid-19/ https://www.imperial.ac.uk/mrc-global-infectious-disease-ana...). A range of 84k to 474k deaths seems pretty reasonable given the U.S. is at something like 90k deaths today.
- blastonico 6y ago
  A range of 84k to 474k seems reasonable? Man, I should have chosen another career area.
  - rrss 6y ago
    Yeah, reasonable, as in: the united states put full suppression measures in place piecemeal sometime between 0.2 and 1.6 deaths / 100k / week (depending on jurisdiction), and the actual number of deaths is trending to end up between the point estimate for putting measures in place at 0.2 deaths / 100k / week and the point estimate for putting measures in place at 1.6 deaths / 100k / week.

AJRF 6y ago

I was really surprised to hear that John Carmack and Github engineers were brought it to clean the code up - after - the government based some of its choices to go in to lockdown. I know more and more of us are getting sucked into the 'tinfoil hat zone' with increasing rapidity thanks to the internet - and you could competently argue I'm going there with this - but that sounds like it was done to maybe downplay fears and the fallout we've seen over the past few weeks around this code and its outsized impact on our current position. It was a 50k LoC monstrosity at one point - in a single file. Neil Ferguson was put in the spotlight as the "source of truth" by the UK media - I get that its more nuanced and I hope the UK government wouldn't have based its decisions to lockdown on this, and they instead took a wide range of data points - but the media pounced on Neils model being the thing that scared Johnson shitless into rolling back the idea of herd immunity. So then people wanted to see the model, and saw it turned out to be horrific in its quality, its lack of testing, and its potentiality to contain mistakes (which it did - given Neil rolled back his predictions after a while) I think that probably spooked some high profile people into action. The whole thing is weird and Neils reputation is in tatters in the media over the way this thing has played out (as well as for some of his extra-curricular activities).

rrss 6y ago
> which it did - given Neil rolled back his predictions after a while Can you please source this? Sorry to have to ask, but last time someone said this it turned out they were comparing predictions in dissimilar scenarios from two different countries.
Yoric 6y ago
> Neil Ferguson was put in the spotlight as the "source of truth" by the UK media - I get that its more nuanced and I hope the UK government wouldn't have based its decisions to lockdown on this, and they instead took a wide range of data points - but the media pounced on Neils model being the thing that scared Johnson shitless into rolling back the idea of herd immunity. Yeah, I read different stories in different newspapers. Such as the rest of the EU, er, politely insisting that the UK was doing something really stupid and needed to change course immediately, not giving Johnson much of a choice. I strongly doubt that the entire EU had based their models on those of a single UK research team.

cnorthwood 6y ago

As far as I can get the argument boils down to "the model is stochastic", "Fortran is old" and "the code is spaghetti". Of which the first one is deliberate, the second one I don't see as a problem, and the last one is definitely a risk factor, but is far from a guarantee that the model is flawed or broken.

Yoric 6y ago
That's also my understanding. I would also be strongly surprised if this was the only study used by, well, most of the world to determine their policies. Even if one study isn't as well-{architected, tested} as a computer engineer would hope (hint: they never are), the fact that pretty much all models/studies lead to the same overall conclusion is quite encouraging.
s9w 6y ago
The code that was released already heavily altered for a month as I recall. And in that state it contained several severe flaws. If you look at it it's painfully obvious that it's just not fit for anything critical. I applaud that they published it. But I also want the consequences: No funding for this quality of work. Also do the opposite of what they say.
jeffbarg 6y ago
My understanding of the frustration is that while the model is deliberately stochastic, there was still unexplained non-determinism in the model that had to be fixed (and still persists). If the randomness isn't fully explained by pre-determined seeds, I'd call that an error.
- tripletao 6y ago
  Here's the GitHub issue: https://github.com/mrc-ide/covid-sim/issues/116 https://github.com/mrc-ide/covid-sim/issues/116 The discussion isn't terribly clear to me. Is this non-determinism in which random number gets used where, like if you seed an RNG once and then use it from multiple threads that get scheduled in varying order? That wouldn't be good, but the model would still be performing as intended, just with no way to make it deterministic for testing. Or is it some other kind of non-determinism? I'm not sure anyone knows, which indeed isn't totally comforting. I'm not sure the "bug uncertainty" is any bigger than all the existing known uncertainty about the assumptions that go in to his (or any such) model, though.

hprotagonist 6y ago

are we whining about only having functional tests still, or have actual bugs been demonstrated that substantively affect model output? If so, what's the link to those issues on their github? the last time this came up it was firmly in the former camp, and was pretty small beer as a result.

deleted 6y ago

[deleted]

deleted 6y ago

[deleted]

calebm 6y ago

Perhaps this should serve as a good case study for why reproducible research is so important.

lerno 6y ago

Yeah you should totally do like Sweden where dead remains at a constant high level and where reduction to a low number of cases per day is very very far away. This “almost lockdown” strategy is almost equally hurtful for the economy but will need to be sustained for much longer.