Basic Concepts
In a nutshell: Discover how variables can be related and how to predict one from another.
## Relationships Between Variables
Sometimes, two variables change together. Correlation measures how strongly they're connected, while regression lets us predict one variable from another.
## What is Correlation?
- A **positive correlation** means both variables increase together.
- A **negative correlation** means as one goes up, the other goes down.
- Correlation values range from -1 to 1.
## What is Regression?
Regression finds the **line of best fit** through a scatterplot, allowing you to predict values. The most common is **linear regression**:
\[
y = mx + b
\]
## Real-World Use
Correlation and regression are used in economics, health care, marketing, and more to predict trends and make decisions.
Examples
- A scientist finds a positive correlation between hours studied and test scores.
- A business uses regression to estimate future sales based on advertising spending.