Transcript 1-Sample t Exercise - Open Source Six Sigma

1-Sample t Exercise
Exercise objective: Utilize what you have learned to
conduct and analyze a one sample t-test using
MINITABTM.
1. The last engineering estimation said we would
achieve a product with average results of 32 parts per
million (ppm).
2. We want to test if we are achieving this performance
level, we want to know if we are on target, with 95%
confidence in our answer. Use data in column “ppm
VOC”
3. Are we on Target?
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1-Sample t Exercise: Solution
Since we do not know the population Standard Deviation, we will use the 1
sample T test to determine if we are at Target.
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1-Sample t Exercise: Solution
After selecting column C1 and
setting “Test mean” to 32.0, click
“Graphs…” and select
“Histogram of data” to get a
good visualization of the
analysis.
Depending on the test you are
running you may need to select
“Options…” to set your desired
Confidence Interval and
hypothesis. In this case the
MINITABTM defaults are what we
want.
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1-Sample t Exercise: Solution
Because the null
hypothesis is within the
confidence level, you
know we will “fail to
reject” the null
hypothesis and accept
the equipment is running
at the target of 32.0.
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Histogram of ppm VOC
(with Ho and 95% t-confidence interval for the mean)
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Frequency
Because we used the
option of “Graphs…” we
get a nice visualization
of the data in a
histogram AND a plot of
the null hypothesis
relative to the
confidence level of the
population Mean.
6
4
2
0
_
X
Ho
20
4
25
30
35
ppm VOC
40
45
50
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1-Sample t Exercise: Solution
In MINITABTM’s Session Window (ctrl – M), you can see the P-value of
0.201. Because it is above 0.05, we “fail to reject” the null hypothesis
so we accept the equipment is giving product at a target of 32.0 ppm
VOC.
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