Statistics for Environmental Engineers

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References


Box, G. E. P., W. G. Hunter, and J. S. Hunter (1978). Statistics for Experimenters: An Introduction to Design, Data Analysis, and Model Building, New York, Wiley Interscience.


Box, G. E. P., G. M. Jenkins, and G. C. Reinsel (1994). Time Series Analysis, Forecasting and Control, 3rd ed., Englewood Cliffs, NJ, Prentice-Hall.


Cryer, J. D. (1986). Time Series Analysis, Boston, MA, Duxbury Press.


Gilbert, R. O. (1987). Statistical Methods for Environmental Pollution Monitoring, New York, Van Nostrand Reinhold.


Montgomery, R. H. and J. C. Loftis, Jr. (1987). “Applicability of the t-Test for Detecting Trends in Water Quality Variables,” Water Res. Bull., 23, 653-662.

Exercises


32.1    Arsenic in Sludge. Below are annual average arsenic concentrations in municipal sewage sludge, measured in units of milligrams (mg) As per kilogram (kg) dry solids. Time runs from left to right, starting with 1979 (9.4 mg/kg) and ending with 2000 (4.8 mg/kg). Calculate the lag 1 autocorrelation coefficient and prepare a scatterplot to explain what this coefficient means.


9.4 9.7 4.9    8.0    7.8    8.0 6.4 5.9 3.7 9.9 4.2


7.0 4.8 3.7    4.3    4.8    4.6 4.5    8.2 6.5 5.8 4.8


32.2    Diurnal Variation. The 70 BOD    values    given    below were measured at 2-h intervals    (time runs


from left to right). (a) Calculate and plot the autocorrelation function. (b) Calculate the approximate 95% confidence interval for the autocorrelation coefficients. (c) If you were to redo this study, what sampling interval would you use?


189


118


157


183


138


177


171


119


118

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