Microsoft Office Tutorials and References

In Depth Information

F12:H13. Be sure to double-check your work or you will not be able to obtain the

correct answer to this problem if you have only one incorrect ﬁgure!

Since both groups have a sample size less than 30, you need to use Formula #2

for the t-test for the difference of the means of two independent samples.

Formula #2 for the two-group t-test is the following:

t
¼
X
1
X
2

S
X
1
X
2

ð
5
:
1
Þ

s

n
1
1

ð

Þ
S
1
þ
n
2
1

ð

Þ
S
2

1

n
1

þ
1

n
2

where S
X
1
X
2
¼

ð
5
:
5
Þ

n
1
þ
n
2
2

and where degrees of freedom
¼
df
¼
n
1
þ
n
2
2

ð
5
:
6
Þ

This formula is complicated, and so it will reduce your chance of making a

mistake in writing it if you ‘‘break it down into pieces’’ instead of trying to write

the formula as one cell entry.

Now, enter these words on your spreadsheet:

E16: (n1-1) x STDEV1 squared

E19: (n2-1) x STDEV2 squared

E22: n
1
? n
2
-2

E25: 1/n
1
? 1/n
2

E28:

s.e.

E31:

critical t

E34:

t-test

B37:

Result:

B40:

Conclusion: (see Fig.
5.15
)

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