# Modeling Population with Regression on a Graphing Calculator

## Key Questions

Using a value called $r$, the regression coefficient.

#### Explanation:

$r$, or the regression coefficient, is a simple value that is used when finding the closeness of a regression equation to the actual data points which it is trying to show a correlation between. $r$ will range from $- 1$ to $1$. The closer the value for a regression equation/model is to $0$, the worse the model will be for showing a trend in the data. So a value closer to $- 1$ or $1$ for $r$ would therefore correspond to a more reliable and accurate equation/model to represent the data.

If you have a graphing calculator, such as a TI-$84$, then your math teacher should be able to help you to find an $r$ value for a regression (or you can just look it up on www.youtube.com).

Just a note for the future: When you are trying to find $r$, a value may appear noted as ${r}^{2}$. This is basically the same concept as $r$, and they both show the closeness of a regression model/equation to the data which it tries to represent. The only difference is that ${r}^{2}$ is $r$ times $r$, or in standard English, the value of the regression coefficient squared.

I hope that helps!