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+---
+id: 2023-12-18
+aliases: December 18, 2023
+tags:
+- link-note 
+- Data-Science
+- Machine-Learning
+- Regularization 
+---
+
+# Regularization
+
+## Regularization Loss Function
+
+- The complexity of the model **$\uparrow$** == the number of model parameters **$\uparrow$**
+- As the complexity of the model **$\uparrow$** == overfitting **$\uparrow$**
+- Define a model with high complexity, learn only important parameters, and set unnecessary parameter values to **0**
+
+## Regularization Types
+
+### Ridge Regression (L2 Regression)
+
+- $L = \bbox[orange,3px] {\sum_{i=1}^{n} (y_i - (\beta_0 + \sum_{j=1}^{D} \beta_j x_{ij}))^{2}} + \bbox[blue,3px] {\lambda \sum_{j=1}^{D} \beta_j^2}$
+	- $\bbox[orange,3px]{\text{MSE}}$
+	- $\bbox[blue,3px]{\text{Ridge}}$
+	- If MSE loss is not reduced, the loss value of the penalty term becomes larger
+	- Lambda $\lambda$ is a hyperparameter that controls the impact of regularization
+	- Normalization function expressed as sum of squares
+
+### Lasso Regression (L1 Regression)
+
+- $L = \sum\limits_{i=1}^{n}(y_{i}- (\beta_{0}+ \sum\limits_{j=1}^{D} \beta_{j}x_{ij}))^{2}+ \lambda \sum\limits_{j=1}^{D} |\beta_j|$
+	- If MSE loss is not reduced, the loss value of the penalty term becomes larger
+	- Lambda $\lambda$ is a hyperparameter that controls the impact of regularization
+	- Normalization function expressed as sum of absolute
+
+![[Pasted image 20231218032332.png]]
+
+## Question
+
+- $\lambda \uparrow$ == Bias error $\uparrow$ and Variance error $\downarrow$
+- Sparsity: Ridge regression $<$ Lasso regression
+- How to make more parameters that have 0 values?
+	1. $\lambda \uparrow$
+	2. Exponent $\downarrow$
+	- Good? or Bad?: don't know
+\ No newline at end of file