t
Tests with Excel
This exercise asks you to look at
the attitude data set used in Chapter 8 and to analyze some data employing the t
test for independent samples. You may complete the assignment by using either SPSS or
Excel. If you wish to use SPSS, do not use this page, but go to the page t Tests with SPSS.
The basic background of the study
was as follows. A researcher was interested in whether non sequitur
fallacies were persuasive. Argumentation theorists will tell you that such
fallacies should not influence people, but they have serious doubts about responses of
people who have never studied fallacies. Thus the directional hypothesis in this
study is that arguments using non sequitur appeals will produce lower levels of
attitude change than arguments not using non sequitur appeals. In this study a
couple of arguments were composed and the experimental treatment consisted of a message
which included non sequitur reasoning focusing on largely irrelevant
information. In the control condition, the non sequitur reasoning was
deleted, leaving a fairly sound argument. These two conditions are the levels of
the independent variable. The variable that identified this fact is
"falexper" (1= with the fallacy presented to subjects; 2=without the fallacy
presented to subjects). The dependent variable is "attitude" toward the
topic (as created in chapter 8), which is the sum of the scores of the scales
"wise-foolish;" "good-bad;" "positive-negative;" and
"beneficial-harmful".
The task in this activity is to
determine if there is a significant difference between the two conditions in this
experiment. Complete a t test with alpha risk at .05, one-tailed.
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conditions must be in separate columns. Thus, we must separate the attitude data into two
columns, one for each group. In column Y row 1 enter "fallwith." In
column Z row 1 enter "fallnone."
Click on cell Y2 (Column Y row 2)
to make it active. From the "Insert" menu, select "Function."
In the "Paste Function" dialog box, click on "Logical in the
"Function Category" field. Click on "If" in the "Function
Name" field and then click "OK." This box should appear as follows:
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In the "Logical_test"
field of the dialog box, enter D2=1" (D is the column in which the
"falexper" is located, 2 is the second row number, and "1" specifies
the condition to be satisfied). In the "Value_if_true" field, enter X2 (to
indicate that we wish the value in cell X2 to be placed in our new cell) and in the
"value_if_false" field enter zero (Excel cannot handle missing values with the t
test function--zeros must be inserted).
Click on cell Y2 to make it
active. On the "Edit" menu click on "Copy." Go to cell Y2 and
hold down the left mouse button while moving down column Y until the end of the data is
reached on row 53. Press Return.
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| Repeat the process for column z.
Click on cell Z2 (column Z, row 2) to make it active. Click on "Insert" menu and
then on "Function." In the "Paste Function" dialog box, click on
"Logical" in the "Function Category" field. Click on "If" in
the "Function Name" field and then click "OK." In the "Logical
Test" field of the dialog box, enter "D2=2" (D is the column in which the
"Falexper" variable is located, 2 is the second row number, and "=2"
specifies the condition to be satisfied). In the "value_if_true" field enter Z2
(to indicate that we wish the value in cell Z2 to be placed in our new cell) and in the
"value_if_false" field enter zero. |
Click on cell Z2 to make it
active. On the "Edit" menu click on "Copy." Go to cell Z2 and hold
down the left mouse button while moving down column Y until the end of the data is
reached. Press Return.
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Excel cannot handle missing
values in the t test function. Thus, students must sort the columns to
create columns with all the data at the top for "FALEXPER" and "fallnone."
From the "Data" menu
click "Sort." Un the ""Sort" dialog box, click the
"Sort by" field and enter "falexper." In the "followed by"
field, enter "fallnone." Click "descending" sorting by for each
of the variables. For "My list has . . .," click "header row."
Click "OK."
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This sort will create one column
with seros above scores. For this column, highlight all the zeros and click ont he
"Edit" menu and click on "Delete." On the "Delete"
dialog box, click on "shift cells up" and click "OK." Now you
have all the data at the top of each column.
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| To compute t,
locate a place to put the output. Go to row 56 column Y and click on the cell to make it
active. From the
"Tools" menu click on "Data Analysis." In the dialog box titled
"Data Analysis" select t-Test: Two Sample Assuming Equal Variances" and
click "OK."
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In the
dialog box "t-test: Two-Sample Assuming Equal Variances" go to the
"Range" field, enter the starting cell and ending cell for the
"fallnone" variable (in this case, $Z$2:$Z$30). Click on the "Output
Range" button and enter the target cell in the field ($Y$56). Click "OK."
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