Here are few notes:
 TrainLogistic uses OnlineLogisticRegression which uses L1 regularization.
You don't say what you are using in R, but I would assume
glm(family="binomial") or equivalent.
Is this correct?
 I don't think that there is a log issue here.
 can you share the data offlist so that I can debug this?
On Wed, Jan 30, 2013 at 7:15 PM, Prabhu <prabhu@mediaiqdigital.com> wrote:
> Thanks, I thought of that, but that doesn't seem to be the right
> explanation
> either
> For one, in the output I see the equation like
> TargetVariable ~ 0.001*InterceptTerm +  0.0006*predictor1 +
> 0.0004*predictor2 ....
>
> Also if I look at the say predictor1, the coefficient in R is 1.02 and for
> predictor2 is 0.48 whereas in Mahout, I get 0.00063 for predictor1 and
> 0.00042 for predictor2. Now if these values are logs of what I am looking
> for, e^ 0.00063 is 0.999937 and e^ 0.00042 is 0.99958, so the difference
> is marginal, whereas R coefficients indicate predictor1 has much higher
> weightage compared to predictor2 which is what I would expect.
>
> Any other thoughts, ideas?
>
> Thanks
> Prabhu
>
> Original Message
> From: Jake Mannix [mailto:jake.mannix@gmail.com]
> Sent: 31 January 2013 04:54
> To: user@mahout.apache.org
> Subject: Re: Logistic Regression in Mahout
>
> Looks like you're looking at weights which are logs of the weights you
> think
> you want.
>
>
> On Wed, Jan 30, 2013 at 4:12 AM, Prabhu <prabhu@mediaiqdigital.com> wrote:
>
> > Hi all,
> >
> > I am trying to use Mahout to run logistic regression analysis on
> > some data. The data is about 7 Million rows, with about 20 predictor
> > variables (all of them numeric). The target variable is Boolean  0 or
> 1.
> >
> > I run a logistic regression with this data on R and I get good
> > coefficients which makes sense. But when I run a logistic regression
> > on the exact same data using Mahout, I get coefficients that don't
> > make sense. For a start, all coefficients are negative. The
> > interesting thing is that the coefficient (from R) for the most
> > important variable (with highest
> > coefficient) has the least negative value in Mahout. Can someone
> > please help me understand what the cause of the problem is?
> >
> >
> >
> > Thanks
> >
> > Prabhu
> >
> >
> >
> >
>
>
> 
>
> jake
>
>
