A Visual and Overly Simplified Guide To Bagging and Boosting

A step-by-step explanation.

Many folks often struggle to understand the core essence of Bagging and boosting. Here’s a simplified visual guide depicting what goes under the hood.

In a gist, an ensemble combines multiple models to build a more powerful model.

They are fundamentally built on the idea that by aggregating the predictions of multiple models, the weaknesses of individual models can be mitigated. Combining models is expected to provide better overall performance.

Whenever I wish to intuitively illustrate their immense power, I use the following image:

Single model vs. Ensemble

Ensembles are primarily built using two different strategies:

1. Bagging

2. Boosting

1) Bagging (short for Bootstrapped Aggregation):

Bagging illustration

• creates different subsets of data (this is called bootstrapping)

• trains one model per subset

• aggregates all predictions to get the final prediction

Some common models that leverage Bagging are:

• Random Forests

• Extra Trees

2) Boosting:

Boosting illustration

• is an iterative training process

• the subsequent model puts more focus on misclassified samples from the previous model

• the final prediction is a weighted combination of all predictions

Some common models that leverage Boosting are:

• XGBoost,

• AdaBoost, etc.

Overall, ensemble models significantly boost the predictive performance compared to using a single model. They tend to be more robust, generalize better to unseen data, and are less prone to overfitting.

👉 Over to you: What are some challenges/limitations of using ensembles? Let’s discuss it today :)

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Find the code for my tips here: GitHub.

I like to explore, experiment and write about data science concepts and tools. You can read my articles on Medium. Also, you can connect with me on LinkedIn and Twitter.