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           Measurement of an Attitude

This assignment asks you to use computers and employ either SPSS or
Excel to explore evidence for reliability of measures. We will give you a
data set from which to work.

Here is a summary of the study from which these data were collected. 
Researchers attempted to determine if there really is anything to the
notion that fallacious reasoning is less persuasive than sound argument
(some wags claim that people are basically irrational [except for them,
of course] and that sound reasoning really does not matter in the
persuasion process).  So a group of researchers took a speech and
developed examples of fallacies to represent informal fallacies in the
family of non sequitur (literally "not in sequence").  Two examples of
each fallacy form were used.  In contrast, a message that deleted the
fallacious arguments was included.  The messages were presented on
two topics to control for topic-subject interaction. 

The hypothesis to be tested was:

   H1: Subjects exposed to persuasive messages including non sequitur
         fallacious reasoning will exhibit lower levels of attitude change 
         than subjects exposed to persuasive message excluding non 
         sequitur fallacious reasoning.

Subjects were presented with the messages and then asked to 
complete a set of
four seven-point semantic differential-type scales:
wise-foolish; good-bad; positive-negative; beneficial-harmful.  These
scales are presumed to measure
attitudes toward the topic.

Identify the level of measurement for the measure of attitude 
change
(you may wish to write your answer to this question your own
or you may wish to use the sheet at the bottom of this web page).

To determine whether the attitude measure is reliable, it is possible
to examine the evidence for it.  To do so, we will compute coefficient
alpha.  Analysis of data is slightly different depending on whether you
use SPSS or Excel to analyze your data.  Instructions for each are
provided below.

If you use SPSS to analyze your data, follow these
instructions:

bulletIf you have not already done so, go to the Data Sets location and
download the file attitude.sav under the list of SPSS Files.
bulletStart your SPSS program.  From the "File" menu load the data file
"ATTITUDE.SAV" from the location where the you saved it after
downloading.
bulletClick on the "Analyze" menu, and on subsequent menus that
appear click on "Scale . . .," and "Reliability Analysis."  In the
"Reliability Analysis" dialog box, click on the names of the
variables that compose the attitude scale:  wise, good,
positive, benefici.  These names appear in the left window 
of the dialog box. Transfer each of these variables to the
window marked "Items:" by clicking on the arrow key in the
middle of the dialog box. 
When you have completed this process the dialog box should
look as follows.

bulletClick on the "Statistics" button.  The following dialog box will
appear.

        To keep things simple, we will ask for essential elements of
        reliability analysis only.  Check the boxes for all three
        "Descriptives" as in the above box.

bulletClick on "Continue" and "OK" in the subsequent dialog box.  Your
data analysis results will appear as output and you may save
these results as a file or simply interpret them directly.

    What is the coefficient alpha for the attitude measure
     (you may wish to write your answer to this question your own
     or you may wish to use the sheet at the bottom of this
     webpage).?

    Once reliable items have been isolated, it is a simple task to add
    the reliable items together to make a composite scale. In SPSS
    this step is completed by using the "Compute" from the
    "Transform" menu.

If you use Excel to analyze your data, follow these
instructions:

bullet

If you have not already done so, go to the Data Sets location and
download the file attitude.xls under the list of Excel Files.

bulletStart your Excel program.  From the "File" menu load the data file
"attitude.xls" from the location where the you saved it after downloading.
  

NOTE:  In Excel, there is no preprogrammed reliability subroutine.
Thus, you must use your own formula. There is more than one way
to use Excel functions, but we will use a rather direct method in this
illustration. In our example, the following steps are taken.

bulletThe formula for coefficient alpha requires that one have a variable
that it is the sum of all the items on the measure. Thus, you
should add the scales that are found in columns E through H on the
spreadsheet. This step is accomplished by moving the cursor to the
nearest empty column (column X in this case) and clicking on the
first row to highlight the cell. In this cell, type "attitude," the label
for the composite scale. Highlight the second row and enter "=."
The formula field above the spreadsheet will be activated. Simply
enter "E2+F2+G2+H2" to identify the columns that are to be added.
Press "Enter" when done.


        To copy this cell down the column, click on the cell and then select
        "Copy" from the "Edit" menu. When the cell is highlighted in this
        fashion, hold down the left mouse button and drag down the column
        until all critical rows are highlighted (through row 53 in this case).

bulletThe formula for coefficient alpha is:

wpe2.jpg (3861 bytes)

To compute coefficient alpha, we must prepare a formula.  For
our data, the following formular applies:

  = ((4)/3) * (1-((VAR(E2:E53))+(VAR(F2:F53))+(VAR(G2:G53))
      +(VAR(H2:H53)))/(VAR(X2:X53))


Note: Though the formula takes more than one line on this page,
it is entered as one long formula.  Do not forget to start the
formula with an equals sign.

bulletTo compute coefficient alpha, we need only find a blank cell (for
instance, cell Y2) and click on it to make it active. Then, the above
formula may be inserted.

 

What is the coefficient alpha for the attitude measure (you may
wish to write your answer to this question your own or you may wish
to use the sheet at the bottom of this webpage).?

Once reliable items have been isolated, it is a simple task to add the
reliable items together to make a composite scale. In Excel, this
operation is completed by moving a new column and creating a new
variable that is the sum of the variables in the indicated columns
containing the reliable measurement items.


Name______________________

 

                     Measurement Comments for Computer Assignment

 

PART A

Go to "Measurement of an Attitude" found on the book website for Chapter 4.
After reading the brief summary of a study dealing with attitude change as
the dependent variable, answer the first set of questions in Part A.

What is the level of measurement for the dependent measure? ___________________________

Of what items is the measure composed?

________________________________________________________________

 

PART B

What is coefficient alpha for the scales identified as the dependent measure? ________________