1.
Exploratory Data Analysis
1.4.
EDA Case Studies
1.4.2.
Case Studies
1.4.2.8.
Heat Flow Meter 1
1.4.2.8.2.

Graphical Output and Interpretation


Goal

The goal of this analysis is threefold:
 Determine if the univariate model:
is appropriate and valid.
 Determine if the typical underlying assumptions for an
"in control" measurement process are valid. These assumptions
are:
 random drawings;
 from a fixed distribution;
 with the distribution having a fixed location; and
 the distribution having a fixed scale.
 Determine if the confidence interval
\( \bar{Y} \pm 2s/\sqrt{N} \)
is appropriate and valid where s is the
standard deviation of the original data.

4Plot of Data


Interpretation

The assumptions are addressed by the graphics shown above:
 The run sequence plot
(upper left) indicates that the data do not
have any significant shifts in location or scale over time.
 The lag plot (upper right)
does not indicate any nonrandom pattern in the data.
 The histogram (lower
left) shows that the data are reasonably symmetric, there does
not appear to be significant outliers in the tails, and it
seems reasonable to assume that the data are from approximately
a normal distribution.
 The normal probability
plot (lower right) verifies that an assumption of normality
is in fact reasonable.

Individual Plots

Although it is generally unnecessary, the plots can be generated
individually to give more detail.

Run Sequence Plot


Lag Plot


Histogram (with overlaid Normal PDF)


Normal Probability Plot

