Dataplot Analysis of a
2**3 Full factorial Design:
Defective Springs
We recommend the following as a bare minimum
Dataplot analysis of a 2**3 full factorial design.
The analysis consists of the following 7 steps:
1. pre-view the data file
2. read in the data
3. generate an effects plot for main factors
4. generate an effects plot for main factors & 2-term interactions
5. generate a matrix of effects plots
6. do a Yates analysis to estimate effects
7. generate a contour plot of the most important 2 factors
Experimental Background
You are a manufacturer of metal springs and you
wish to reduce the number of defective springs per
batch. You suspect that 3 factors are affecting
the number of defectives: the temperature of the
oven for making the steels, the carbon
concentration of the steel, and the temperature of
the quenching temperature after the steel is
removed from the oven. You run a 2**3 full
factorial design (8 runs) in which
Y = response variable = % acceptable per batch
X1 = oven temperature (1450 and 1600 degress F)
X2 = carbon concentration (.5 and .7%)
X3 = quenching temperature (70 and 120 degrees F)
Your objective of course to determine which of
these factors (and interactions) effect the %
acceptable springs, and ultimately to determine
the settings of the factors which maximize the
percent acceptable springs.
Dataplot has several hundred auxiliary data files
(ASCII) that have been provided for user perusal
and which contain a variety of interesting data
sets. The names of the available Dataplot
auxiliary data files are in the file
DATASETS.TEX
You can thus scan Dataplot's available auxiliary
data file names by entering any of the following 3
equivalent commands:
VIEW DATASETS.TEX
PREVIEW DATASETS.TEX
LIST DATASETS.TEX
Hypothetical data from the above 2**3 defective
springs experiment has been placed in the Dataplot
auxiliary file BOXSPRIN.DAT. This example and
data were drawn from the manuscript [Box &
Bisgaard, 19xx]
1. Preview the data file
You can view the contents of the ASCII data file
BOXSPRIN.DAT by entering:
VIEW BOXSPRIN.DAT
The following will appear on your screen: