Learning Outcomes:
The student will:
line of best fit (trend line) - A line on a scatter plot
which can be drawn near the points to more clearly show the trend between two sets of data
Line of Best Fit
 The correlation coefficent (r)
ranges between -1 and 1. It is part of the following applet, but will not critical
to this lesson. It is useful, however to help us understand the strength of data
correlations.
| Correlation |
Strong |
Weak |
- Positive
- up and right
|
0.7 to 1.0 |
0.3 to 0.7 |
- Negative
- down and left
|
-1.0 to -0.7 |
-0.7 to -0.3 |
Little or No Correlation: -0.3 to
0.3 |
| Directions: Use the following to plot points on a
scatter plot. Click on the grid several times and observe what happens to the line
of best fit for a linear relationship. Click the "Clear Points" button. Click
on two points on the grid. The points will be connected by a line. See what
happens if you click on other points on the line.
Click the "Clear Points" button. Click on two points on the grid. The
points will be connected by a line. See what happens if you click on grid points
that are not on the line.
- Click and drag data points to change there positons.
- The value of r is the correlation coefficent. It ranges between -1 and 1.
It is part of the applet, but will not be emphasized in this lesson. It
is useful, however to help us understand the strength of data correlations.
source: http://ictcm.tamu.edu/Wisconsin_2001/Scatterplot/
|
Directions: Use the following to examine 3
scatterplot samples and to create your own scatterplots.
- Click the "Load Data File" button to see the first scatterplot sample.
The other two samples are available from the pulldown menu. To display the sample,
click the "Load Data File" button after selecting a sample. Click on various
spreadsheet cells and change the values. Notice the effect the change has on the
line of best fit.
- Create your own scatterplots by entering the data points into the spreadsheet to the
left of the graph.
- The correlation coefficent ranges between -1 and 1. It is part of the applet,
but will not be emphasized in this lesson.
- The slope and intercept of the line of best fit is given, but will not be emphasized
in this lesson.
source: http://math.hws.edu/javamath/config_applets/index.html |
| Directions: Use the following to plot points on a
scatter plot. Click on the grid several times and observe what happens to the line
of best fit for a linear relationship. Click the "Clear Points" button. Click
on two points on the grid. The points will be connected by a line. See what
happens if you click on other points on the line.
Click the "Clear Points" button. Click on two points on the grid. The
points will be connected by a line. See what happens if you click on grid points
that are not on the line.
- Click and drag data points to change their positons.
- The value of r is the correlation coefficent. It ranges between -1 and 1.
It is part of the applet, but will not be emphasized in this lesson. It
is useful, however to help us understand the strength of data correlations.
To interpolate, click a point on the line between
the outer most points on the curve.
To extrapolate, click a point on line of best fit
outside of the other points on the curve.
source: http://ictcm.tamu.edu/Wisconsin_2001/Scatterplot/
|
Directions: Use the following to examine 3
scatterplot samples and to create your own scatterplots.
- Click the "Load Data File" button to see the first scatterplot sample.
The other two samples are available from the pulldown menu. To display the sample,
click the "Load Data File" button after selecting a sample. Click on various
spreadsheet cells and change the values. Notice the effect the change has on the
line of best fit.
- Create your own scatterplots by entering the data points into the spreadsheet to the
left of the graph.
- The correlation coefficent ranges between -1 and 1. It is part of the applet,
but will not be emphasized in this lesson.
- The slope and intercept of the line of best fit is given, but will not be emphasized
in this lesson.
To interpolate, plot the point on the line between
the outer most points on the curve.
To extrapolate, plot the point on curve of best
fit outside of the other points on the curve.
source: http://math.hws.edu/javamath/config_applets/index.html |
|
