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https://issues.apache.org/jira/browse/MADLIB-1317?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16818226#comment-16818226
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Orhan Kislal commented on MADLIB-1317:
--------------------------------------
w/ [~khannaekta]
Hi Pratik,
One hot encoding is the preferred way to handle categorical independent
variables for multinomial regression. Closing this JIRA per your confirmation.
Let us know if you have any other questions.
> Multinomial results not matching with R method
> ----------------------------------------------
>
> Key: MADLIB-1317
> URL: https://issues.apache.org/jira/browse/MADLIB-1317
> Project: Apache MADlib
> Issue Type: Bug
> Components: Module: Multinomial Logistic Regression
> Reporter: Pratik
> Priority: Major
>
> Hi team,
> I have using madlib multinomial method on my dataset with categorical
> independent variable (hot encoded) as below.
>
> {code:java}
> SELECT
> CASE WHEN multinom IS NOT NULL THEN TRUE ELSE FALSE END
> FROM
> madlib.multinom(
> 'TEMP_TEST_1',
> 'TEMP_TEST_1_OP',
> 'dep_var_col',
> 'ARRAY[ 1,hot_encoded_GENDER_col_val1, hot_encoded_GENDER_col_val2]',
> '1',--REF CATEGORY
> 'logit',
> NULL,
> 'max_iter=100,optimizer=irls,tolerance=0.0001',
> TRUE
> );{code}
> Gender being a categorical column I am hot encoding it in 2 columns 0|1.
> When comparing results with R's method coefficients match but the StdErr and
> pValue are way off in comparison.
> R method -
> {code:java}
> nnet::multinom
> {code}
>
> Is there anything I need to do specially for multinom or is it a bug?
> Or is there perticular way I need to use R to compare results with multinom?
> *UPDATE:*
> Is it mandatory to have ref_category like column for categorical independent
> variable??
> hot encoded GENDER_col_val1 from list of independent variable and results are
> matching with Rs output.
>
> Is there any documentation or reference to confirm this?
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