Machine Learning Pitfall: Avoiding Misleading Accuracy in Imbalanced Datasets

I used a simple Python chart today and it reminded me why accuracy can be misleading in machine learning. When a dataset is imbalanced (one class appears way more than the other), a model can look “good” just by predicting the majority class most of the time. Here’s what I did : 1. Plotted the class distribution 2. Checked what a “dumb baseline” accuracy would be if I always predicted the majority class 3. Decided to focus more on Precision, Recall, F1, and ROC-AUC instead of accuracy alone If 90% of the data is one class, a model can get ~90% accuracy while being useless for the minority class (which is often the important one). So, what I've learned is Before training any model, I now always do: Class distribution plot Baseline check Choose metrics that match the real goal ❓ Quick question In a high-stakes problem (fraud, health, risk), would you prioritise precision or recall — and why? #DataScience #MachineLearning #Python #DataVisualization #BuildInPublic

  • chart, bar chart

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