Figure 4b 13: Plot of residuals from the aircraft primer paint experiment versus
application method.

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Figure 4b 14: Plot of residuals from the aircraft primer paint experiment versus
predicted values
ijk
.
Self-Help
In understanding the lesson, the book “Statistics and Probability (2016) by
Bateller R., Statistics and Probability theory by Cruz M et al” can be utilized.
Topics under
ULO
4a
can
also
be
accessed
through
this
link
chapter14.html
Several statistics and probability books can also be downloaded online that can be
used to gather more examples and for future reference.
Let’s Check
Knowledge
1.
An engineer suspects that the surface finish of metal parts is influenced by the type of
paint used and the drying time. He selected three drying times
—
20, 25, and 30 minutes
—
and used two types of paint. Three parts are tested with each combination of paint type
and drying time. The data are as follows:
(a) State the hypotheses of interest in this experiment.
(b) Test the hypotheses in part (a) and draw conclusions using the analysis of variance with
α = 0.05.
(c) Analyze the residuals from this experiment.

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Phone No.: (082)300-5456/300-0647 Local 133
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2. In the book
Design and Analysis of Experiments
, 8th edition (2012, John Wiley & Sons), the
results of an experiment involving a storage battery used in the launching mechanism of a
shoulder-fired ground-to-air missile were presented. Three material types can be used to make
the battery plates. The objective is to design a battery that is relatively unaffected by the
ambient temperature. The output response from the battery is effective life in hours. Three
temperature levels are selected, and a factorial experiment with four replicates is run. The data
are as follows:
(a) Test the appropriate hypotheses and draw conclusions using the analysis of variance with
α = 0.05.
(b) Graphically analyze the interaction.
(c) Analyze the residuals from this experiment.
Let’s
Analyze
Knowledge
1.
An experiment was conducted to determine whether either firing temperature or
furnace position affects the baked density of a carbon anode. The data are as follows:
(a) State the hypotheses of interest.
(b) Test the hypotheses in part (a) using the analysis of variance with α = 0.05. What
are your conclusions?
(c) Analyze the residuals from this experiment.
(d) Using Fisher's LSD method, investigate the differences between the mean baked
anode density at the three different levels of temperature. Use α = 0.05.</