The Advantages and Disadvantages of PCA To Consider Before Using It

A quick pros and cons summary of PCA.

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PCA is possibly the most popular dimensionality reduction technique.

If you wish to know how PCA works, I have a highly simplified post here: A Visual and Overly Simplified Guide to PCA.

Yet, it is equally important to be aware of what we get vs. what we compromise when we use PCA.

The above visual depicts five common pros and cons of using PCA.

Advantages

1. By reducing the data to two dimensions, you can easily visualize it.

2. PCA removes multicollinearity. Multicollinearity arises when two features are correlated. PCA produces a set of new orthogonal axes to represent the data, which, as the name suggests, are uncorrelated.

3. PCA removes noise. By reducing the number of dimensions in the data, PCA can help remove noisy and irrelevant features.

4. PCA reduces model parameters: PCA can help reduce the number of parameters in machine learning models.

5. PCA reduces model training time. By reducing the number of dimensions, PCA simplifies the calculations involved in a model, leading to faster training times.

Disadvantages

1. The run-time of PCA is cubic in relation to the number of dimensions of the data. This can be computationally expensive at times for large datasets.

   

   PCA run-time.

2. PCA transforms the original input variables into new principal components (or dimensions). The new dimensions offer no interpretability.

3. While PCA simplifies the data and removes noise, it always leads to some loss of information when we reduce dimensions.

4. PCA is a linear dimensionality reduction technique, but not all real-world datasets may be linear. Read more about this in my previous post here: The Limitation of PCA Which Many Folks Often Ignore.

5. PCA gets affected by outliers. This can distort the principal components and affect the accuracy of the results.

Over to you: What are some points that I have missed here? Let me know :)

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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.