LFD Book Forum Question 7-9: all overwhelms one, should we use weights

#1
09-17-2012, 06:55 AM
 vtrajan@vtrajan.net Junior Member Join Date: Jul 2012 Posts: 5
Question 7-9: all overwhelms one, should we use weights

Dear Prof:
I questions 7-9, in one vs all, the number of all instances is about 9 times the number of one, so it overwhelms the one. The results are skewed in one direction. Should we use different weights to compensate for this? Give weights for each class proportional to 1/number of instances?

As it stands now, I am not sure the answers are that meaningful.

But I would guess that the answers that the system accepts assumes that there is no weighting of the classes, each instance has the same weight.

Rajan
#2
09-17-2012, 08:41 AM
 yaser Caltech Join Date: Aug 2009 Location: Pasadena, California, USA Posts: 1,477
Re: Question 7-9: all overwhelms one, should we use weights

Quote:
 Originally Posted by vtrajan@vtrajan.net Dear Prof: I questions 7-9, in one vs all, the number of all instances is about 9 times the number of one, so it overwhelms the one. The results are skewed in one direction. Should we use different weights to compensate for this? Give weights for each class proportional to 1/number of instances?
In general some weighting can be used to balance different classes. This is not done in this problem for the sake of simplicity.
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