Microsoft Office Tutorials and References

In Depth Information

Throughout this topic, we are assuming that you want to be 95% conﬁdent in the

results of your statistical tests. Therefore, the value for t in the t-table in Appendix E

tells you whether or not the t-value you obtained when you used the formula for the

one-group t-test is within the 95% interval of the t-curve range that that t-value

would be expected to occur with 95% conﬁdence.

If the t-value you obtained when you used the formula for the one-group t-test is

inside
of the 95% conﬁdence range, we say that the result you found is
not

signiﬁcant
(note that this is equivalent to
accepting the null hypothesis!)
.

If the t-value you found when you used the formula for the one-group t-test is

outside
of this 95% conﬁdence range, we say that you have found a
signiﬁcant

result
that would be expected to occur less than 5% of the time (note that this is

equivalent to
rejecting the null hypothesis and accepting the research hypothesis
).

4.1.6 STEP 6: State the result of your statistical test

There are two possible results when you use the one-group t-test, and only one of

them can be accepted as “true.”

Either: Since the absolute value of t that you found in the t-test formula is
less

than the critical value of t
in Appendix E, you accept the null hypothesis.

Or: Since the absolute value of t that you found in the t-test formula is
greater

than the critical value of t
in Appendix E, you reject the null hypothesis, and accept

the research hypothesis.

4.1.7 STEP 7: State the conclusion of your statistical

test in plain English!

In practice, this is more difﬁcult than it sounds because you are trying to summarize

the result of your statistical test in simple English that is both concise and accurate

so that someone who has never had a statistics course (such as your boss, perhaps)

can understand the result of your test. This is a difﬁcult task, and we will give you

lots of practice doing this last and most important step throughout this topic.

If you have read this far, you are ready to sit down at your computer and perform

the one-group t-test using Excel on some hypothetical data.

Let’s give this a try.

4.2 One-group t-test for the mean

The American Institute of Biological Sciences (AIBS) is a non-proﬁt scientiﬁc

association dedicated to advancing biological research and education. It has more

than 150 member organizations. AIBS publishes a peer-reviewed monthly journal

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