Population Statistics I
Homework 5
Ambient water quality data were obtained from several sites in the wetlands
near Lake Charles, LA and reported by the
Louisiana Department of Environmental Quality. In some instances, the pH
was unavailable for a particular date. If so, the previous month's value was then used
to impute a value for the missing data (note: this may not be the best imputation
method to use). Use the data from these
sites to build sample mean, standard deviation, and range Shewhart control
charts for water pH as determined from the field measurements. Next, assume
that it is known from lots of historical data that the average pH in these
waters should be 7.0. Construct a CUSUM chart using these same data using
7.0 as the target mean value. Write an executive summary of your findings.
Does it appear that the pH process is reasonably constant through time and
"in control"? What other information might you like to have available to you
that could be relevant to monitoring water quality through time at these
sites? How might you use this information?
The data are incorporated into the attached
SAS program to help you with the data input.
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Last Modified: April 18, 2001