Data Science

The Confusion Matrix

SQL Mastery Team
June 17, 2026
5 min read

Welcome to **Day 147**. Accurate models can still be dangerous.

The Scenarios

1. **False Positive**: The doctor says you're pregnant, but شما're a man. (Annoying, but not fatal).

2. **False Negative**: The security alarm doesn't go off during a robbery. (**Catastrophic**).

The Confusion Matrix

It's a 2x2 grid that shows:

  • **True Positives**: Correctly predicted "Yes."
  • **True Negatives**: Correctly predicted "No."
  • **False Positives**: Incorrectly predicted "Yes."
  • **False Negatives**: Incorrectly predicted "No."
  • from sklearn.metrics import confusion_matrix

    cm = confusion_matrix(y_test, predictions)

    sns.heatmap(cm, annot=True)

    Precision vs Recall

  • **Precision**: When I say it's Spam, how often am I right?
  • **Recall**: Of all the Spams out there, how many did I actually catch?
  • Your Task for Today

    Generate a confusion matrix for your classification model and identify how many "False Positives" it produced.

    *Day 148: K-Means Clustering (Unsupervised Learning).*

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