
I. Enter your data into two
columns in the data file
 Use the first column of the data file
to show SPSS the difference between your two conditions. Use two different
numbers to represent each of your two conditions. For example, use 1s to
represent the first condition and 2s to represent the second condition.
 Give the first column of data a
meaningful name. It’s a good idea to use the letters “IV” in this name.
 Use the second column of the data
file to type the data collected for each participant in each condition. Make
sure that data for the first condition goes next to the numbers that you used
to represent the first condition in the first column. Similarly, make sure
that the data for the second condition goes next to the numbers that you used
to represent the second condition in the first column.
 Give the second column of data a
meaningful name. It’s a good idea to use the letters “DV” in this name.
 Save the data file to a meaningful
place with a meaningful name. This file should have a .sav extension.
 Click Analyze, Compare Means and then
Independent Samples T Test. An Independent Samples T Test box will appear.
 Move your IV to the Grouping Variable
box by highlighting it and clicking on the corresponding arrow.
 Click the Define Groups button. A
Define Groups box will appear.
 Define the conditions of your
experiment by telling SPSS the numbers you used to represent the first and
second condition of your experiment.
 Click Continue. The Define Groups box
will disappear and you will be back to the Independent Samples T Test box.
 Move your DV into the Test Variables
box by highlighting it and clicking on the corresponding arrow.
 Click OK and wait a few seconds for
processing.
 Save the output to a meaningful place
with a meaningful name. SPSS should give the output file a .spo extension.
 Look in the Group Statistics box for
condition means, standard deviations and number of participants.
 Make sure the number of participants
for each condition is accurate. If it is not, go back to the data file and
make sure it is correct.
 Look in the Independent Samples Test
box.
 Determine which of the two rows to
read from by checking the Sig. value in the Levene’s Test for Equality of
Variances column. If the Sig. value is greater than .05, read from the top
row. If the Sig. value is less than or equal to .05, read from the bottom row.
 Check the Sig (2Tailed) value in the
appropriate row to determine if there was a statistically significant
difference between group means. If the Sig (2Tailed) value is greater than
.05, you can conclude that there is no statistically significant difference
between your two conditions – that the IV did not have a significant effect on
the DV. However, if the Sig (2Tailed) value is less than or equal to .05, you
can conclude that there is a statistically significant difference between your
two conditions. This means that it is likely that the IV did have an effect on
the DV and the results were not likely due to chance.
 Report the type of test used and what
it was used to test.
 Report whether or not there was a
significant difference between your conditions. Include the group means,
standard deviation, and the Ttest values.
 Report your results in words that
people can understand.
Background 
Enter Data 
Analyze Data 
Interpret Data 
Report Data
