# chi-squared statistics returned by RapidMiner

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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

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

0

## Answers

1,751RM Founderall class based weights are summed up.

Cheers,

Ingo

2Contributor II 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

344UnicornI would be interested in this, too...

any way to look into the source code?

129RM EngineeringThe 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.

5University ProfessorHope to get help concerning this.