Regression Correlation F2E365
1. The problem is to understand the concepts of regression and correlation in statistics.
2. Regression analysis is used to model the relationship between a dependent variable $y$ and one or more independent variables $x$. The simplest form is linear regression, which uses the formula:
$$y = mx + b$$
where $m$ is the slope and $b$ is the intercept.
3. Correlation measures the strength and direction of a linear relationship between two variables. The correlation coefficient $r$ ranges from $-1$ to $1$:
- $r = 1$ means perfect positive correlation.
- $r = -1$ means perfect negative correlation.
- $r = 0$ means no linear correlation.
4. Important rules:
- Correlation does not imply causation.
- Regression predicts the value of $y$ given $x$.
- The closer $|r|$ is to 1, the stronger the linear relationship.
5. Example: Given data points, calculate the regression line and correlation coefficient by:
- Finding means of $x$ and $y$.
- Calculating slope $m = \frac{\sum (x_i - \bar{x})(y_i - \bar{y})}{\sum (x_i - \bar{x})^2}$.
- Calculating intercept $b = \bar{y} - m\bar{x}$.
- Calculating correlation $r = \frac{\sum (x_i - \bar{x})(y_i - \bar{y})}{\sqrt{\sum (x_i - \bar{x})^2 \sum (y_i - \bar{y})^2}}$.
This process helps understand how variables relate and predict outcomes.