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Learning from Imbalanced Classes

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1–10 of 14 posts

Re: Learning from Imbalanced Classes

#2
Solid article. Especially important are the suggestions to consider a probabilistic evaluation metric.

If you want to work with really imbalanced data, try working with data from the LHC. There were on order of 1000 Higgs in a year, while there are around 600 million proton-proton collisions a second.

Re: Learning from Imbalanced Classes

#3
In addition to unbalanced classes, where let's say 2% of data is from a minority class and 98% is from the majority, how do people handle when 2% of data is from the minority and 98% is of an unknown class, but pulled from a known distribution?

Re: Learning from Imbalanced Classes

#4
post #3

In addition to unbalanced classes, where let's say 2% of data is from a minority class and 98% is from the majority, how do people handle when 2% of data is from the minority and 98% is of an unknown class, but pulled from a known distribution?

https://en.wikipedia.org/wiki/Semi-supervised_learning

Re: Learning from Imbalanced Classes

#5

Solid article. Especially important are the suggestions to consider a probabilistic evaluation metric. If you want to work with really imbalanced data, try working with data from the LHC. There were on order of 1000 Higgs in a year, while there are around 600 million proton-proton collisions a second.

LHC data = EPIC

Re: Learning from Imbalanced Classes

#8
post #5

Solid article. Especially important are the suggestions to consider a probabilistic evaluation metric. If you want to work with really imbalanced data, try working with data from the LHC. There were on order of 1000 Higgs in a year, while there are around 600 million proton-proton collisions a second.

LHC data = EPIC

This is one of those few moments when saying Big Data is actually a well-used term.

Re: Learning from Imbalanced Classes

#9
post #3

In addition to unbalanced classes, where let's say 2% of data is from a minority class and 98% is from the majority, how do people handle when 2% of data is from the minority and 98% is of an unknown class, but pulled from a known distribution?

I am not completely following what you mean by "98% is of an unknown class, but pulled from a known distribution".

Are you suggesting that: 2 percent of samples are positive, drawn from p(x|y=1)

98 percent of samples are drawn from a distribution p(x), but may be either positive or negative?

The setting that you described above is called "positive and unlabeled (PU)" learning. This paper: http://cseweb.ucsd.edu/~elkan/posonly.pdf is one of the seminal articles on the topic (although the equation on the bottom of page 214 contains a statement that may not necessarily hold true). There are quite a lot more recent papers on this topic.

Re: Learning from Imbalanced Classes

#10
post #3

In addition to unbalanced classes, where let's say 2% of data is from a minority class and 98% is from the majority, how do people handle when 2% of data is from the minority and 98% is of an unknown class, but pulled from a known distribution?

I am not completely following what you mean by "98% is of an unknown class, but pulled from a known distribution". Are you suggesting that: 2 percent of samples are positive, drawn from p(x|y=1) 98 percent of samples are drawn from a distribution p(x), but may be either positive or negative? The setting that you described above is called "positive and unlabeled (PU)" learning. This paper: http://cseweb.ucsd.edu/~elka…

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