The correlated *t*-test is used whenever we have two groups
in either a within-subjects or a matched subjects design. For the
purpose of illustration, we will use the data that appears in Table
11.1 of the text. This table presents the data for three groups, but
we will act as if there were only two groups (10 distracters and 15
distracters) to illustrate the correlated samples *t*-test.

The file Table_11-1.sav is on
website and can be
downloaded to your computer. To open the file containing the data
from Table 11.1, we use the File menu and select the *Open*
option. This screen shows the data set
we will be working with. We have already named and formatted each of
the variables for you.

To run a correlated samples *t*-test, you select the Analyze
menu, the Compare Means submenu, and the *Paired Samples T Test*
option, which will give you this screen. You
need to highlight the two variables (in this case, ten and fifteen)
and move them into the right box using the arrow between the boxes
as shown in this screen. Note that you can
ONLY move the two variables as a pair. You cannot move them one
variable at a time. Clicking on OK will then run the analysis giving
you the results shown in this screen.

Note again, that for the data shown in Table 11.1 of the text
(three conditions in a within-subjects design), the appropriate
analysis is a repeated measures ANOVA. We
used only two of the three groups to illustrate the correlated
samples *t*-test, even though this would not be the optimal
data analysis choice. We did this solely for the purpose of
illustrating how you would go about computing a paired samples *t*-test.

We have prepared an animation that will walk you through this procedure. To run an animation, simply click on the title of the animation in the table below.

Note that we do not recommend that you try to run the animations if you have a slow connection, such as a dial-up connection. You will find that the animations take forever to load with a slow connection.