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Available Chlorine

Keywords: nonlinear regression, pure error, goodness of fit


The data are from a Proctor and Gamble study reported by Smith and Dubey (1964) on the amount of available chlorine in a product as a function of time since manufacture. Theoretical considerations lead to the model

Chlorine = a + (0.49 - a) exp{ -b (Weeks - 8) }

Variable Description

Weeks Time in weeks since manufacture
Chlorine Available chlorine


Data File (tab-delimited text)


Jennrich, R. I., and Bright, P. B. (1976). Fitting systems of linear differential equations using computer generated exact derivatives. Technometrics 18, 385-392.
Jennrich, R. I. (1995). An Introduction to Computational Statistics. Prentice-Hall, Englewood Cliffs, New Jersey. Section 8.2.1.


The plot gives the data and the theoretical curve fitted by least squares:

Chlorine vs Weeks with fitted curve (10109 bytes)



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