[program-l] Re: Python: How do I evaluate if my decision tree is overfitting

  • From: <pranav@xxxxxxxxxxxxxxxxx>
  • To: <program-l@xxxxxxxxxxxxx>
  • Date: Mon, 3 Jan 2022 16:37:53 +0530

Hi Dzhovani,

Many thanks. I have been trying the approach you outline with respect to 
feature engineering. <smile


Pranav

-----Original Message-----
From: program-l-bounce@xxxxxxxxxxxxx <program-l-bounce@xxxxxxxxxxxxx> On Behalf 
Of Dzhovani Chemishanov
Sent: Monday, January 3, 2022 3:34 PM
To: program-l@xxxxxxxxxxxxx
Subject: [program-l] Re: Python: How do I evaluate if my decision tree is 
overfitting

Hi,
Show new data to your model. If the results are significantly worse than those 
on the training data, you are overfitting. Especially if it is giving you false 
negatives. Underfitting is if you have too many false positives.

The way to find the most significant features is to drop some of them and see 
how much it will alter your results. The more the absence of a feature affects 
the results, the more significant it is. If you see no change, then the feature 
is insignificant.
HTH,
Dzhovani

On 1/2/22, pranav@xxxxxxxxxxxxxxxxx <pranav@xxxxxxxxxxxxxxxxx> wrote:

Hi all,

I have built a decision tree in python using the sklearn library. How 
do I evaluate if  it is overfitting or underfitting?

I also need to do some feature engineering in terms of determining 
which features are contributing most to my model. I am thinking about 
using the shap values but if I print them, I get numbers which I am 
not sure how to interpret.

Pranav

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