No contexto de classification tasks in inteligência artificial and aprendizado de máquina, Macro-Média is a method used to evaluate the performance of a model across multiple classes. Unlike Micro-Média, which aggregates the contributions of all classes to compute the average performance, Macro-Average treats each class equally regardless of its tamanho.
Para calcular a Média Macro, você primeiro calcula a métrica de avaliação (such as precision, recall, or F1-score) for each class individually. Then, you take the arithmetic mean of these scores across all classes. This approach ensures that each class has an equal weight in the final average, which can be particularly important in scenarios where class distributions are imbalanced.
For instance, consider a scenario with three classes: Class A (100 instances), Class B (10 instances), and Class C (5 instances). A model may perform exceedingly well on Class A and poorly on Classes B and C. If you only look at precisão geral, it might seem like the model is performing well. However, Macro-Average will highlight the poor performance on the minority classes, providing a more balanced view of the model’s effectiveness.
Embora a Média Macro seja útil para compreensão do desempenho do modelo in multi-class settings, it is essential to consider it alongside other metrics, particularly when dealing with imbalanced datasets, to get a comprehensive view of a model’s performance.