# Principal Component Analysis (PCA)

YouTube search... ...Google search

- AI Solver
- ...find outliers
- Clustering
- Anomaly Detection
- Dimensional Reduction
- T-Distributed Stochastic Neighbor Embedding (t-SNE) ..non-linear
- Causation vs. Correlation - Multivariate Additive Noise Model (MANM)
- Independent Component Analysis (ICA) | University of Helsinki
- Linear Non-Gaussian Acyclic Model (ICA-LiNGAM) | S. Shimizu, P. Hoyer, A. Hyvarinen, and A. Kerminen - University of Helsinki
- Greedy DAG Search (GDS) | Alain Hauser and Peter Biihlmann
- Feature-to-Feature Regression for a Two-Step Conditional Independence Test | Q. Zhang, S. Filippi, S. Flaxman, and D. Sejdinovic

a data reduction technique that allows to simplify multidimensional data sets to 2 or 3 dimensions for plotting purposes and visual variance analysis.

- Center (and standardize) data
- First principal component axis
- Across centroid of data cloud
- Distance of each point to that line is minimized, so that it crosses the maximum variation of the data cloud

- Second principal component axis
- Orthogonal to first principal component
- Along maximum variation in the data

- First PCA axis becomes x-axis and second PCA axis y-axis
- Continue process until the necessary number of principal components is obtained

## NumXL