To tell apart strong and weak relationships in two sets of data, we look at scatter graphs and correlation coefficients.

1. Scatter Graphs: These graphs help us see how the data points relate to each other.

   • Strong Correlation: When the data points are close together and form a straight line, like this:
     • (Think of a line where $r$ is about 1 or -1)
   • Weak Correlation: If the points are spread out and don’t form a clear line, it means there's no strong connection:
     • (Here, $r$ would be around 0)

2. Correlation Coefficient (r): This is a number that shows how strong the relationship is and whether it’s positive or negative.

   • Understanding the Values:
     • Between 0.0 and 0.3: This means a weak relationship.
     • Between 0.3 and 0.7: This shows a moderate relationship.
     • Between 0.7 and 1.0: This indicates a strong relationship.

3. Line of Best Fit: This is a special line drawn through the data that helps us see the overall trend.

   • The way this line slopes tells us if the relationship is going up (positive) or down (negative).