1. Lesson 6-7 Scatter Plots and Lines of Best Fit

2. Scatter Plots A scatter plot is a graph that relates two different sets of data by plotting the data as ordered pairs. The data is usually real world driven, and may not form a perfect line. People will analyze the data for trends, and will construct a trend line or line of best fit through the approximate center of data points.

3. Generalizations of Trends How close are the data points to the line of best fit?  Very Close – High Correlation  Not Close – Low Correlation Is the line increasing as the data numbers increase (slope of the line of best fit)?  Yes – Positive Correlation  No – Negative Correlation

4. Generalizations of Trends - Examples

6. What happens if you can’t draw a line that would pass through the center of the data? Then there’s no correlation

7. Line of Best Fit Line of Best Fit – the line drawn through the best estimation of the center of the data. Always use the line’s points when determining the slope, equation, etc. Is used to make predictions about any input variable by interpolating (connecting between) the data points.

8. Line of Best Fit - Example

9. To get a linear equation use the line’s coordinates: (26,25) and (10,10) - NOT ANY DATA POINTS. Slope: (25-10)/(26-10) = 15/16 Intercept : 0 Linear Equation: y = (15/16)x + 0

10. Assignment Worksheet photocopy of page 83 numbers 21 and 26.