Microsoft Office Tutorials and References
In Depth Information
For example, suppose that you tested college freshmen males on the perceived
effectiveness of ‘‘Ibuprofen’’ versus ‘‘Acetaminophen,’’ in which the males were
randomly assigned to use just one of these types of pain medication, and then to
rate its perceived effectiveness on a 100-point scale from 0 = poor to
100 = excellent. After the research study was completed, suppose that the
Ibuprofen group had 52 males in it, their mean effectiveness rating was 55 with a
standard deviation of 7, while the Acetaminophen group had 57 males in it and
their average effectiveness rating was 64 with a standard deviation of 13.
The formulas for analyzing these data to determine if there was a significant
different in the effectiveness rating for freshmen males for these two types of pain
medication require you to use six numbers correctly in the formulas: the sample
size, the mean, and the standard deviation of each of the two groups. All six of
these numbers must be used correctly in the formulas if you are to analyze the data
correctly.
If you create a table to summarize these data, a good example of the table, using
both Step 1 and Step 2, would be the data presented in Fig. 5.1 :
Fig. 5.1 Basic table format
for the two-group t-test
For example, if you decide to call Group 1 the Ibuprofen group and Group 2 the
Acetaminophen group, the following table would place the six numbers from your
research study into the proper cells of the table as in Fig. 5.2 :
Fig. 5.2 Results of entering
the data needed for the
two-group t-test
You can now use the formulas for the two-group t-test with more confidence
that the six numbers will be placed in the proper place in the formulas.
Note that you could just as easily call Group 1 the Acetaminophen group and
Group 2 the Ibuprofen group; it makes no difference how you decide to name the
two groups; this decision is up to you.
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