# ISL: Linear Regression - Part 1

Yao Yao on September 21, 2014

## 0. Overview

Linear Regression is a supervised learning approach, especially useful for predicting a quantitative response.

It serves to answer these questions:

1. Is there a relationship, between$X$ and $Y$?
2. How strong is the relationship?
3. Which $x_i$’s contribute to $Y$?
4. How accurately can we estimate the effect of each $x_i$ on$Y$?
5. How accurately can we predict future $Y$?
6. Is the relationship linear?
• 非常好的一个问题，回归问题本质
7. Is there synergy among $x_i$’s?