You are solving a classification problem with a highly imbalanced class. The majority class is occurring 98% of times in the training data.Now when you come with predictions, your model has 98% accuracy on test data. Which of the following is true in such a case?1. Accuracy metric is not a good idea for imbalanced class problems.2. Accuracy metric is a good idea for imbalanced class problems.3. Precision and recall metrics are good for imbalanced class problems.4. Precision and recall metrics aren’t good for imbalanced class problems.
Question
You are solving a classification problem with a highly imbalanced class. The majority class is occurring 98% of times in the training data.Now when you come with predictions, your model has 98% accuracy on test data. Which of the following is true in such a case?1. Accuracy metric is not a good idea for imbalanced class problems.2. Accuracy metric is a good idea for imbalanced class problems.3. Precision and recall metrics are good for imbalanced class problems.4. Precision and recall metrics aren’t good for imbalanced class problems.
Solution
- Accuracy metric is not a good idea for imbalanced class problems.
- Precision and recall metrics are good for imbalanced class problems.
In an imbalanced class problem, accuracy is not a good metric because the model can achieve a high accuracy by simply predicting the majority class all the time. For example, in this case, if the model predicts the majority class for all instances, it would be correct 98% of the time, hence the 98% accuracy. However, this model would be useless for predicting the minority class, which is often the class of interest in imbalanced problems.
On the other hand, precision and recall are more informative metrics for imbalanced class problems. Precision measures the proportion of true positive predictions among all positive predictions, while recall measures the proportion of true positive predictions among all actual positives. These metrics give a better indication of the model's performance on the minority class.
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