Machine Learning Tutorial 0/98 lessons ~6 min read Lesson 6

    Data Cleaning

    What is Data Cleaning?

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    Focus
    7 guided sections
    Practice signal
    Examples included
    Career prep
    Foundation builder

    Introduction

    What is Data Cleaning? Handle missing values, outliers, duplicates, and invalid entries before modeling. Machine learning systems learn patterns from data instead of hard-coded rules.

    Understanding the topic

    How Data Cleaning works:

    • Handle missing values, outliers, duplicates, and invalid entries before modeling.
    • Prepare or explore data as needed.
    • Train or apply the model/technique.
    • Evaluate results and iterate.
    TermDescription
    Data CleaningHandle missing values, outliers, duplicates, and invalid entries before modeling
    Training dataExamples used to learn patterns.
    FeaturesInput variables (columns) fed to the model.
    Target / labelWhat you predict (supervised learning).

    Step-by-step explanation

    1. Understand — Learn when and why to use Data Cleaning.
    2. Prepare data — Load, clean, and split datasets.
    3. Apply — Fit model or run algorithm in Python/sklearn.
    4. Evaluate — Measure accuracy, loss, or cluster quality.

    Execution workflow

    1Data Cleaning workflow
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    Understand

    Learn when and why to use Data Cleaning.

    Best practices

    • Split data into train/validation/test before tuning.
    • Scale numeric features when algorithms are distance-based.
    • Always evaluate on held-out data — not training accuracy alone.

    Common mistakes

    • Training on test data (data leakage).
    • Ignoring class imbalance in classification metrics.
    • Using accuracy alone on imbalanced datasets.

    Summary

    Data Cleaning is a core machine learning topic. Handle missing values, outliers, duplicates, and invalid entries before modeling

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