Chapter – Scatter Plots and Correlation

Scatter plot – graph of a set of data pairs (x, y) Correlation – relationship between the ordered pairs Positive Negative Relatively none

2.7 – Scatter Plots and Correlation Positive Correlation As x increases, y tends to increase

2.7 – Scatter Plots and Correlation Negative Correlation As x increases, y tends to decrease

2.7 – Scatter Plots and Correlation Relatively no correlation There is no obvious pattern between x and y

2.7 – Scatter Plots and Correlation Example 1 Describe the correlation shown.

2.7 – Scatter Plots and Correlation Example 2 Describe the correlation shown

2.7 – Scatter Plots and Correlation Best – fitting line – A line that most closely models a set of data

2.7 – Scatter Plots and Correlation Steps for Approximating a best-fitting line Draw a scatter plot Sketch a line that follows the trend of the data. It should be close to as many points as possible. Choose 2 points that line on the line. Write an equation of the line that passes through the two points

2.7 – Scatter Plots and Correlation Example 3 The table gives the systolic blood pressure y of patients x years old. Approximate the best- fitting line for data. X y

2.7 – Scatter Plots and Correlation Example 4 These data represent purchases at five gas stations in a city Gallons Cost ($)

2.7 – Scatter Plots and Correlation Example 4 (cont) Approximate the best-fitting line Predict the cost of 10.0 gallons of gas in the city Gallons Cost ($)

2.7 – Scatter Plots and Correlation HOMEWORK 2.7 Practice A Worksheet