# Regression

Document Sample

```					                      Modeling Using Cubic Regression

Copy the data set below into Excel:
x             y
-0.2          4.2
0.3          3.7
0.9         -0.98
2.3          -3.8
2.9          6.87

Create a scatterplot (y vs x) of the data in Excel and paste your graph
below:

Find a quadratic regression model ( y  ax 2  bx  c ) for the data and
report the model below. What is the value of r-squared for this model?



Find a cubic regression model ( y  ax 3  bx 2  cx  d ) for the data and
report the model below. What is the value of r-squared for this model?



Which model is a better fit for the data? How do you know?

Use the superior model to predict the value of y when x=0.
Modeling Using Cubic Regression

Real Estate The table shows the average price (in thousands of dollars) of a
house in the Northeastern U.S. for 1987 to 1995. Let t be the number of
years since 1987.
t           f(t)
0           140
1           149
2          159.6
3           159
4          155.9
5           169
6          162.9
7           169
8           180

Create a scatterplot (Average Home Price vs. Year) of the data in Excel and

Find a quadratic regression model ( y  ax 2  bx  c ) for the data and
report the model below. What is the value of r-squared for this model?


Find a cubic regression model ( y  ax 3  bx 2  cx  d ) for the data and
report the model below. What is the value of r-squared for this model?



Which model is a better fit for the data? How do you know?

Use the superior model to predict the price of a home in the year 2000.
Modeling Using Cubic Regression

Space Exploration The table shows the average speed y (in feet per
second) of a space shuttle for different times t (in seconds) after launch.

t           y
10         202.4
20         463.4
30         748.2
40         979.3
50         1186.3
60         1421.3
70         1795.4
80         2283.5

Create a scatterplot (Average Speed vs Time after Launch) of the data in
Excel and paste your graph below:

Find a quadratic regression model ( y  ax 2  bx  c ) for the data and
report the model below. What is the value of r-squared for this model?



Find a cubic regression model ( y  ax 3  bx 2  cx  d ) for the data and
report the model below. What is the value of r-squared for this model?



Which model is a better fit for the data? How do you know?

Use the superior model to determine the speed of the space shuttle 100
seconds after the launch.

```
DOCUMENT INFO
Shared By:
Categories:
Stats:
 views: 4 posted: 5/28/2011 language: English pages: 3