nerdexam
IBM

C2090-930 · Question #41

You have a poorly performing risk model and are looking for strategies to improve performance. You know that only about one percent of your cases represent risk, and you have over 1 million cases to…

The correct answer is D. Use the Ensemble node to reduce the number of non-risky cases used to train the model by a. Option D is correct because when facing severe class imbalance (1% vs 99%) in a large dataset, an Ensemble approach addresses the problem by creating multiple balanced subsets from the non-risky (majority) cases, training separate models on each balanced subset, and combining…

Modeling Techniques

Question

You have a poorly performing risk model and are looking for strategies to improve performance. You know that only about one percent of your cases represent risk, and you have over 1 million cases to use for training purposes. What is the correct approach to test for improving performance?

Options

  • AUse the Time Series node to reduce the number of all cases by a factor of 100.
  • BUse the CHAID node to reduce the number of all cases used to train the model by half.
  • CUse the Balance node to reduce the number of non-risky cases used to train the model by a
  • DUse the Ensemble node to reduce the number of non-risky cases used to train the model by a

How the community answered

(62 responses)
  • A
    3% (2)
  • B
    15% (9)
  • C
    8% (5)
  • D
    74% (46)

Explanation

Option D is correct because when facing severe class imbalance (1% vs 99%) in a large dataset, an Ensemble approach addresses the problem by creating multiple balanced subsets from the non-risky (majority) cases, training separate models on each balanced subset, and combining their predictions. This leverages the full scale of the 1M+ dataset without permanently discarding majority-class information - a critical advantage with such extreme imbalance.

Option A is wrong because the Time Series node is designed for sequential/temporal data forecasting, not class balancing. Reducing all cases by a factor of 100 preserves the same 1:99 imbalance ratio, so the model still sees the same skewed distribution.

Option B is wrong because CHAID is a decision tree modeling algorithm - it classifies data, it does not sample or balance training sets. It cannot be used as a data preparation strategy.

Option C is wrong because while the Balance node can undersample the majority class, a simple halving still leaves a roughly 1:49 ratio - still severely imbalanced. Ensemble resampling is the more statistically robust tool when imbalance is this extreme and data is abundant.

Memory tip: Think "E for Ensemble = Equal exposure" - with millions of cases and severe imbalance, Ensemble methods give the minority class equal exposure across multiple training rounds, rather than a one-shot undersample that wastes data or still leaves imbalance.

Topics

#class imbalance#Balance node#Ensemble node#model performance

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