So sánh phương pháp

	Phân tích phân biệt bậc hai (QDA)	Phân tích biệt số tuyến tính (LDA)
Lĩnh vực	Học máy	Học máy
Họ	Latent structure	Latent structure
Năm ra đời	1939	1936
Người khởi xướng	Classical Gaussian discriminant analysis (Fisher / Welch lineage)	Fisher, R. A.
Loại	Generative Gaussian classifier	Supervised dimensionality reduction and linear classifier
Công trình gốc	Hastie, T., Tibshirani, R., & Friedman, J. (2009). The Elements of Statistical Learning (2nd ed.). Springer. ISBN: 978-0-387-84857-0	Fisher, R. A. (1936). The use of multiple measurements in taxonomic problems. Annals of Eugenics, 7(2), 179–188.
Tên gọi khác	QDA, quadratic classifier, kuadratik diskriminant analizi	LDA, Fisher's discriminant analysis, Fisher linear discriminant, normal discriminant analysis
Liên quan	2	4
Tóm tắt	Quadratic discriminant analysis is a generative classifier that models each class with its own multivariate Gaussian distribution, allowing each class a separate covariance matrix. Unlike linear discriminant analysis, which assumes a shared covariance and yields linear boundaries, QDA's per-class covariances produce curved (quadratic) decision boundaries, letting it capture differences in the spread and orientation of the classes.	Linear Discriminant Analysis is a supervised method for dimensionality reduction and classification, introduced by Ronald A. Fisher in 1936, that finds linear combinations of features which maximally separate predefined classes while preserving as much class-discriminatory information as possible. It simultaneously serves as a feature-projection technique and a probabilistic classifier, making it one of the foundational methods in pattern recognition and statistical learning.