Microsoft Office Tutorials and References

In Depth Information

5.1 The 9 STEPS for Hypothesis-Testing

Using the Two-Group t-Test

Objective: To learn the 9 steps of hypothesis-testing using two groups of

people, plants, or animals and the two-group t-test

You will see that these steps parallel the steps used in the previous chapter that

dealt with the one-group t-test, but there are some important differences between

the steps that you need to understand clearly before we dive into the formulas for

the two-group t-test.

5.1.1 STEP 1: Name One Group, Group 1, and the Other Group,

Group 2

The formulas used in this chapter will use the numbers 1 and 2 to distinguish

between the two groups. If you deﬁne which group is Group 1 and which group is

Group 2, you can use these numbers in your computations without having to write

out the names of the groups.

For example, if you are testing the perceived effectiveness of two different types of

pain medications on college freshmen males, you could call the groups: ‘‘Ibuprofen’’

and ‘‘Acetaminophen,’’ but this would require your writing out the words ‘‘Ibupro-

fen’’ and ‘‘Acetaminophen’’ whenever you wanted to refer to one of these groups.

If you call the Ibuprofen group, Group 1, and the Acetaminophen group, Group 2,

this makes it much easier to refer to the groups because it saves you writing time.

As a second example, you could be comparing ﬂower preference for one type of

hummingbird. Two types of ﬂowers, fuschias and mandevillas, have a vibrant red

color that is a typical attractant found in hummingbird gardens. If you had to write

out the names of the two ﬂowers whenever you wanted to refer to them, it would

take you more time than it would if, instead, you named one ﬂower, Group 1, and

the other ﬂower, Group 2.

Note, also, that it is completely arbitrary which group you call Group 1, and

which Group you call Group 2. You will achieve the same result and the same

conclusion from the formulas however you decide to deﬁne these two groups.

5.1.2 STEP 2: Create a Table that Summarizes the Sample Size,

Mean Score, and Standard Deviation of Each Group

This step makes it easier for you to make sure that you are using the correct numbers

in the formulas for the two-group t-test. If you get the numbers ‘‘mixed-up,’’ your

entire formula work will be incorrect and you will botch the problem terribly.

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