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chi-squared statistics returned by RapidMiner

Hello,

I tried to use Rapid Miner to compute Chi-squared weights of a set of attributes.

Chi-squared weights are locally defined, i.e. computed with respect to a given class, and the local weights of an attribute are sometimes combined to give a single global weight of the attribute (e.g. by summing up all of its local weights, and taking its max local weight).

My question is, how is the single chi-squared weight returned by RapidMiner computed?

Thank you very much.

Best Regards
CW

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IngoRM

Hi,

all class based weights are summed up.

Cheers,
Ingo

ironfrown

I have been chasing this up for while as well. I am still not clear on your answer.

How do you derive Weight from Chi-Squared for two variables X and Y? I imagine we construct a contingency table of "r" rows (corresponding to all classes of variable X) and "c" columns (corresponding to all classes of variable Y). I have no issue calculating Chi-Squared statistic of X and Y independence. How do you get the weight for X and Y from this?

Jacob

Fred12

I would be interested in this, too...

any way to look into the source code?

mmichel

The core of RapidMiner Studio is open source and available at github: https://github.com/rapidminer/rapidminer-studio

If you want to get a better understanding of the 'Weight by Chi Squared Statistic' operator, you can find the implementation details here.

User42010

I would like to know the formula used to calculate the weights generated by chi-square.

Hope to get help concerning this.