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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 conclusion 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.

Objective: To write the conclusion of the conﬁdence interval about the mean

test

Let’s set some basic rules for stating the conclusion of a hypothesis test.

Rule #1:

Whenever you reject H
0
and accept H
1
, you must use the word

‘‘signiﬁcantly’’ in the conclusion to alert the reader that this test found

an important result.

Rule #2:

Create an outline in words of the ‘‘key terms’’ you want to include in

your conclusion so that you do not forget to include some of them.

Rule #3:

Write the conclusion in plain English so that the reader can understand

it even if that reader has never taken a statistics course.

Let’s practice these rules using the Chevy Impala Excel spreadsheet that you

created earlier in this chapter, but ﬁrst we need to state the hypotheses for that car.

If General Motors wants to claim that the Chevy Impala gets 28 miles per

gallon on a billboard ad, the hypotheses would be:

H
0
: l = 28 mpg

H
1
: l = 28 mpg

You will remember that the reference value of 28 mpg was inside the 95 %

conﬁdence interval about the mean for your data, so we would accept H
0
for the

Chevy Impala that the car does get 28 mpg.

Objective: To state the result when you accept H
0

Result: Since the reference value of 28 mpg is inside the conﬁdence interval, we

accept the null hypothesis, H
0

Let’s try our three rules now:

Objective: To write the conclusion when you accept H
0

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