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> The shear wave echoes from a single seismogram are difficult to distinguish from random noise, so the researchers used a machine-learning algorithm originally

by jl6 6y ago

> The shear wave echoes from a single seismogram are difficult to distinguish from random noise, so the researchers used a machine-learning algorithm originally designed for identifying trends in large astronomy data sets. How does one convince oneself that such a machine-learning algorithm is finding genuine signal in the noise, rather than just generating echoes of its training data?

Groxx 6y ago
Though I don't know for this one, a semi-common strategy is to use ML to efficiently search for "interesting" datapoints, and then verify with conventional tools. In that sort of use, it doesn't really matter if it's hallucinating - it'll just produce a lot of false-positives and you'll go (╯°□°)╯︵ ┻━┻ and try something else instead.
- Retric 6y ago
  Anything generating a lot of possible ‘interesting’ datapoints is very tricky to statistically validate. Essentially you need to raise the threshold for statistical significance based on the number of possibilities being considered. That’s almost never done correctly, and often misused. https://en.wikipedia.org/wiki/Data_dredging https://en.wikipedia.org/wiki/Data_dredging
aaron695 6y ago
I asked this question if it really was Machine Learning last time this was posted and I don't think it was (Feel free to correct me) It's - http://sequencer.org/ http://sequencer.org/ Pseudo-code - http://sequencer.org/static/images/image1.png http://sequencer.org/static/images/image1.png I find it much more exciting than ML because it's both real and seems to be a simple online service for scientists, which is pretty cool. A video on it - https://www.youtube.com/watch?v=KN-N7l5spmE https://www.youtube.com/watch?v=KN-N7l5spmE
- mturmon 6y ago
  On a cursory look it seems to construct a distance matrix between all pairs of items, and look for a spanning tree with that distance metric that is "elongated" - i.e., less branching. Straightforward enough. There seems to be a bit more, involving iterating over different scales and over different distance metrics, but that's not particularly principled or efficient.
- faizshah 6y ago
  The github has a good overview of the algo(and clean python code): https://github.com/dalya/Sequencer https://github.com/dalya/Sequencer

by jl6 6y ago

Groxx 6y ago

Though I don't know for this one, a semi-common strategy is to use ML to efficiently search for "interesting" datapoints, and then verify with conventional tools. In that sort of use, it doesn't really matter if it's hallucinating - it'll just produce a lot of false-positives and you'll go (╯°□°)╯︵ ┻━┻ and try something else instead.

Retric 6y ago
Anything generating a lot of possible ‘interesting’ datapoints is very tricky to statistically validate. Essentially you need to raise the threshold for statistical significance based on the number of possibilities being considered. That’s almost never done correctly, and often misused. https://en.wikipedia.org/wiki/Data_dredging https://en.wikipedia.org/wiki/Data_dredging

aaron695 6y ago

I asked this question if it really was Machine Learning last time this was posted and I don't think it was (Feel free to correct me) It's - http://sequencer.org/ http://sequencer.org/ Pseudo-code - http://sequencer.org/static/images/image1.png http://sequencer.org/static/images/image1.png I find it much more exciting than ML because it's both real and seems to be a simple online service for scientists, which is pretty cool. A video on it - https://www.youtube.com/watch?v=KN-N7l5spmE https://www.youtube.com/watch?v=KN-N7l5spmE

mturmon 6y ago
On a cursory look it seems to construct a distance matrix between all pairs of items, and look for a spanning tree with that distance metric that is "elongated" - i.e., less branching. Straightforward enough. There seems to be a bit more, involving iterating over different scales and over different distance metrics, but that's not particularly principled or efficient.
faizshah 6y ago
The github has a good overview of the algo(and clean python code): https://github.com/dalya/Sequencer https://github.com/dalya/Sequencer