1. 2.5 USING LINEAR MODELS

2. 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.

3. 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 points
4. Look for correlation

4. 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?

5. 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 plot
2. Sketch the trend line
3. Choose two points on the sketch for step 2
4. Write an equation of a line for the two points chosen

6. EXAMPLE: PAGE 94


7. 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.

8. ASSIGNMENTS
 Classwork
 2.5 Worksheet
 Homework
 Page 96
 3, 6, 7 – 11odd, 18