Gráfico de Levantamento
Um Gráfico de Levantamento é uma representação gráfica usada em modelagem preditiva and mineração de dados to assess the performance of a classification model. It compares the model’s ability to correctly identify positive cases against random selection. The chart illustrates how much better the model performs than random guessing, which is crucial for evaluating the effectiveness of the model in real-world applications.
The x-axis of a Lift Chart typically represents the percentage of the total population, sorted by the predicted probability of being a positive case, while the y-axis shows the lift, which is the ratio of the observed positive cases to the expected positive cases if selected randomly. The lift is calculated as:
- Levantamento = (Taxa de Verdadeiro Positivo) / (Taxa Base)
Where the True Positive Rate is the proportion of actual positives that the model correctly identifies, and the Base Rate is the overall proportion of positives in the dataset.
A well-constructed Lift Chart provides insights into how well the model can discriminate between positive and negative classes. The area under the curve indicates the model’s performance; a higher lift value reflects a better model. For instance, if a model achieves a lift of 3 in the top 10% of predicted probabilities, it means the model is three times more effective than random selection within that group.
Os Gráficos de Levantamento são especialmente úteis em campanhas de marketing, pontuação de crédito, and gestão de riscos, where making accurate predictions can lead to significant business advantages. By utilizing Lift Charts, data scientists and analysts can refine their models, optimize targeting strategies, and ultimately improve decision-making processes.