Small-scale sentiment classification often suffers
from data scarcity, which limits the generalization ability of
the models. This study evaluates and compares the effectiveness
of three data augmentation strategies: Easy Data Augmenta-
tion (EDA), back-translation, and contextual token substitution
(nlpaug-style), with both traditional machine learning classifiers
(Logistic Regression, Random Forest) and transformer-based
models (BERT). We perform a comprehensive empirical com-
parison with low-resource sentiment datasets by summarizing
the results of recent studies and performing targeted head-to-
head experiments. Our findings indicate that all augmentation
methods improve performance. Contextual augmentation yields
the most consistent gains for BERT models, while EDA and back-
translation provide greater benefits for traditional classifiers.
These insights help guide the selection of data augmentation
techniques tailored to model type and dataset size, filling a critical
gap in research on data augmentation for sentiment classification
on small datasets.
