Contents
What is the class imbalance problem in the given data set?
Definition. Data are said to suffer the Class Imbalance Problem when the class distributions are highly imbalanced. In this context, many classification learning algorithms have low predictive accuracy for the infrequent class. Cost-sensitive learning is a common approach to solve this problem.
How do you overcome class imbalance?
7 Techniques to Handle Imbalanced Data
- Use the right evaluation metrics.
- Resample the training set.
- Use K-fold Cross-Validation in the right way.
- Ensemble different resampled datasets.
- Resample with different ratios.
- Cluster the abundant class.
- Design your own models.
How do you balance a dataset imbalance?
What does imbalance data and small training sets mean?
Imbalanced data refers to where the number of observations per class is not equally distributed and often there is a major class that has a much larger percentage of the dataset and minor classes which doesn’t have enough examples. Small Training Sets also suffer from not having enough examples.
How to deal with an imbalanced training set?
The idea of balancing the training set + validating the balancing method is for being able to generalize your model that is would discriminate (in classification assignment) better a sample from the minority class, in an unseen and imbalanced test set.
How is the degree of class imbalance determined?
Since class labels are required in order to determine the degree of class imbalance, class imbalance is typically gauged with respect to the training distribution. — Page 16, Imbalanced Learning: Foundations, Algorithms, and Applications, 2013. It is common to describe the imbalance of classes in a dataset in terms of a ratio.
How to deal with a class imbalance dataset?
If you are sampling randomly for the training and testing, then the ratio is still 90:10 in the testing set. If your model is very biased , that predicts all the samples to be class A , then: Overall accuracy = 90% Average accuracy = 50 % ( 100% for class A + 0% for class B) / 2