Minitab Lab #4
Math 120
Nguyen 1 of 5
Objectives: Calculate a correlation coefficient between two variables
Perform a regression analysis between two variable
Sketch a scatter plot, a fitted line plot and a residual plot.
Click on: Start > All Programs > Minitab 14 For Windows > Minitab 14
Note: In the following instructions underlined words indicate what information you type in.
IMPORTANT: Do the following command only once. Please be patient. It can take MiniTab awhile to load
when everyone is starting Minitab at the same time.
A. Steps to open (or retrieve) a saved project:
1. Click on: File > Open Project …
In the Open Project window:
a. Click on the down arrow in the Look-in: box and select the K: drive > NatrlSci folder > GNguyen
b. Double click on Lab Four.MPJ
2. On the screen in the worksheet window you should see the following columns :
Age
Boy Height
Girl Height
B. Steps to save your project:
1. Click on: File > Save Project As …
In the Save Project As window:
a. In the Save in: box, select the H: drive
b. In the File Name box, type: Lab Four – your name
c. Click on the Save button
C. Steps to draw a scatter plot.
1. Click on: Graph  Scatterplot …
In the Scatterplots window:
a. Click on the Simple button
b. Click on the OK button
In the Scatterplot – Simple window:
a. Double click on Boy Height in the box on the left to
pump this variable to the Row 1, Y Variables cell in the
graph table on the right.
b. Double click on AGE in the box on the left to pump this
variable to the Row 1, X Variables cell in the graph table
on the right.
c. Click on the OK button
Minitab Lab #4
Math 120
You should see the scatter plot displayed to the right.
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Close Button
2. Close the graph window.
a. When prompted to save this graph, click
“No”.
D. Save your project : Click on the save file icon
E. Steps to calculate the correlation coefficient of the data set
1. Click on:
Stat  Basic Statistics  Correlation…
In the Correlation window:
a. Double click on Age in the box on the left to pump this
column to the Variables box on the right.
b. Double click on Boy Height in the box on the left to
pump this column to the Variables box on the right.
c. Un-check on the box in front of “Display p-values”
d. Click on the OK button
2. In the Session window, you should see
the correlation coefficient displayed to
the right:
Results for: Lab Two
Scatterplot of Boy Height vs Age
Correlations: Age, Boy Height
Pearson correlation of Age and Boy Height =
0.949
F. Save your project: Click on the save file icon
G. Steps to calculate the regression equation of the data set and sketch a residual plot.
Minitab Lab #4
Math 120
1. Click on:
Stat  Regression  Regression…
In the Regression window:
a. Double click on Boy Height in the box on the left to
pump this column to the Response box on the right.
b. Double click on Age in the box on the left to pump
this column to the Predictors box on the right.
c. Click on the Results button
2. In the Regression - Results window:
a. Click on the button to the left of
In addition, the full table of fits and
residuals.
Note: The fits are the corresponding y-hat
values.
b. Click on the OK button
When you return to the Regression window:
a. Click on Graphs button
3. In the Regression - Graphs window:
a. Under Residuals for Plots:
Click on the button to the left of Regular.
b. Under Residual Plots:
Click on the button to the left of Individual
plots
c. Click in the Residuals versus the variables: box
d. Double click on Age in the box on the left to
pump this variable into this box.
e. Click on the OK button
When you return to the Regression window:
a. Click on the OK button
You should see the residual plot displayed to the
right.
4. Close the plot window.
a. When prompted to save this plot, click “No”.
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Minitab Lab #4
Math 120
Nguyen 4 of 5
In the Sessions window,
you should see part of the
regression analysis displayed on
the right.
5. To maximize this window to see
the entire analysis:
Maximize Button
a. Click on the maximize button
(the button in the middle in the
upper right hand corner of this
window)
b. Click on the up arrow on the
scroll bar on the right edge until
you see the regression equation.
c. When you have finished reading
the regression analysis:
Click on the restore button
(the button in the middle in the
upper right hand corner of this
window)
Restore Button
Up Arrow
H. Save your project: Click on the save file icon
I. Steps to draw the regression line in the scatter diagram and other diagnostic graphs
1. Click on: Stat  Regression  Fitted Line Plot
…
In the Fitted Line Plot window:
a. Double click Boy Height in the box on the left to
pump this column to the Response (Y) box on the
right.
b. Double click on Age in the box on the left to pump
this column to the Predictor (X) box on the right.
c. Under Type of Regression Model:
Click on the button to the left of Linear.
d. Click on the Graphs … button
Minitab Lab #4
Math 120
Nguyen 5 of 5
In the Fitted Line Plot - Graphs window:
a. Under Residuals for Plots
Click on the button to the left of Regular.
b. Under Residual Plots
Click on the button to the left of Four in one.
c. Click on the OK button
When you return to the Fitted Line Plot window
a. Click on the OK button
You should see the four residual plots to the right
displayed in one window.
Are you impressed?
I wanted to show you that there are many other
things to consider in the analysis of a regression.
But we don’t have time in this class to study them.
2. Close this window
a. When prompted to save this window, click “No”.
Now you should see the scatter plot and the
regression line.
2. To insert your name on the graph and print it:
a. Right-click on the title, select Add  select
Title…  type in your name following the title
b. Print the Graph: The graph bar should be blue;
if it is not, highlight the graph (Click on the graph
bar, the bar turns blue) then to the menu
File>Print graph
J. Save your project: Click on the save file icon
K. Repeat Steps C thru J, using Age as the predictor variable again, and using Girl Height as the response
variable, instead of Boy Height. (Every where Boy Height is mentioned, double click on Girl Height instead.)
L. Save your project : Click on the save file icon
M. Print the session window. Make sure to type Your Name on the Session window screen. Type a TITLE
PAGE (using MS Word), include Lab Title, Date, Your Name, and Analysis (in your Analysis, compare the two
regression lines, indicate which one has a better fit, why it has a better fit, which is a significant relationship, etc.).
Staple in this order: Title page, Session window, and the 2 Plots.
N. Exit Minitab and end your computer session by logging off.