11.7 Scatter Plots

11.7 Scatter Plots

Quick Refresh:

• What is the slope of this line?

• What is the y-intercept of this line?

Multiple Choice

Which of the following graphs is the best match for this equation?

Multiple Select

Which of the following statements are true about the line of best fit? Select all that apply

• The slope is positive

• The slope is negative

• The y-intercept is zero

• The line passes through the point (4,9)

• The line passes through the point (5,12)

Interpreting Scatter Plots

• The equation for the line of best fit is

   $y=4x-2$  

• What does the slope mean in the context of the graph?

• What does the y-intercept mean in the context of the graph?

Residuals and Correlation Coefficients

• Residuals - points that don't line up well with the line of best fit

• Correlation Coefficients 

• Stronger when there are fewer residuals

• Weaker when there are more residuals

Multiple Choice

Which scatter plot has a stronger correlation coefficient?

Changing the correlation coefficient

• Correlation Coefficients exist on a scale of -1 to +1-- closer to -1 is weaker, closer to +1 is stronger

  The current correlation coefficient of this graph is -0.7

• If the point (1,40) is added to the graph, is it going to make the correlation coefficient stronger or weaker?