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vtrajan@vtrajan.net 09-17-2012 06:55 AM

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

yaser 09-17-2012 08:41 AM

Re: Question 7-9: all overwhelms one, should we use weights
 
Quote:

Originally Posted by vtrajan@vtrajan.net (Post 5410)
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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