2.5 USING LINEAR MODELS

SCATTER PLOTS

A Scatter Plot is a graph that relates two set of data by plotting ordered pairs. Scatter plots can be used to determine the

“strength” of the relationship between data sets, this is called correlation.

MAKING A SCATTER PLOT

1. Decide which variable is the independent variable (x) and which is the dependent variable (y).

2. Create axes in the appropriate units based on your table of values (remember if you do not start an axis at zero you need to use the changing scale symbol)

3. Plot points4. Look for correlation

EXAMPLE: PAGE 93 The table lists average monthly temperature

and electricity costs for a home in Texas in 2008. The table displays the values. Make a scatter plot. How would you describe the correlation?

TREND LINE

A trend line is a line that approximates the relationship between the variables or data sets. Can be used to make predictions

To find the equation of the trend line:1. Create the scatter plot2. Sketch the trend line 3. Choose two points on the sketch for step 24. Write an equation of a line for the two points

chosen

EXAMPLE: PAGE 94 The table shows the median home prices in Florida. What is

the equation of the trend line that models the relationship between time and price? Use the equation to predict the median home price for 2020. For the scatterplot, let correspond to 1940.

TREND LINE VS LINE OF BEST FIT

The trend line is an approximation. The line of best fit is the most accurate

trend line and it found using technology.

ASSIGNMENTS

Classwork 2.5 Worksheet

Homework Page 96 3, 6, 7 – 11odd, 18