TMVA, BDT, Rank Variable : Variable Importance nan

Dear experts,

I face a problem with the raking of my variables in a BDT and any help would be very much appreciated!

In some of the configurations I tried this is what I see [1] and I would like to understand why I get “nan”.
(while in other configurations I get values for the rank of the variables). Do you think that I can trust those configurations for which I get “nan” in the ranking, or I should just discard them?
Also in these configurations the Kolmogorov-Smirnov test is not 0, and the separation of signal/ background is quite nice!
Please note that although all the variables are doubles, the : Border_accepted, Sec_str_accepted, Extra_new_accepted are having a boolean behaviour, so they are either 1, or 0.

The configuration of this BDT is [2].

thank you very much in advance,
Kostas

[1]
— BDT3 : Ranking result (top variable is best ranked)
— BDT3 : ----------------------------------------------------
— BDT3 : Rank : Variable : Variable Importance
— BDT3 : ----------------------------------------------------
— BDT3 : 1 : Border_accepted : -nan
— BDT3 : 2 : Sec_str_accepted : -nan
— BDT3 : 3 : Extra_new_accepted : -nan
— BDT3 : 4 : Oms3 : -nan
— BDT3 : 5 : Oms3_in_coinc : -nan
— BDT3 : 6 : Oms3_with_angular : -nan
— BDT3 : 7 : Tot_beh_vtx : -nan
— BDT3 : 8 : Oms3_beh_vtx : -nan
— BDT3 : 9 : Ratio_tot : -nan
— BDT3 : 10 : Ratio_pulses : -nan
— BDT3 : ----------------------------------------------------

[2]
factory->BookMethod( TMVA::Types::kBDT, “BDT3”,"!H:!V:NTrees=900:MinNodeSize=0.5%:MaxDepth=4:BoostType=AdaBoost:AdaBoostBeta=0.5:UseBaggedBoost:BaggedSampleFraction=0.1:SeparationType=GiniIndex:nCuts=18" );

Hi Kostas,

You shouldn’t ignore the nan’s. I suggest that you post this question to the TMVA users forum:

sourceforge.net/p/tmva/mailman/tmva-users/

Cheers,

Sergei

Dear Sergei,

Thank you for your reply!
I have already sent an email to the tmva-users mailing list at the 5 of December (so it is already posted to the link you mentioned) but I didn’t have any reply yet, so I tried this, more general, forum.

Cheers,
Kostas