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Exhaust from Burning Ethanol

Keywords: nonparametric regression, semiparametric regression


This dataset is distributed with S-Plus as the dataframe ethanol.

The engine exhaust was analysed in an experiment in which ethanol was burned in a single cylinder automobile test engine. The response variable is NOx, the concentration of nitric oxide (NO) and nitrogen dioxide (NO2) in the engine exhaust, normalized by the work done by the engine. The explanatory variables are the compression ratio of the engine and the equivalence ratio at which the engine was run - a  measure of the richness of the air/ethanol mix.

Variable Description

NOx Concentration of nitric oxide (NO) and nitrogen dioxide (NO2)
Compression Compression ratio
Equivalence Equivalence ratio


Data File (tab-delimited text)


Brinkman, N. D. (1981). Ethanol Fuel - A single-cylinder engine study of efficiency and exhaust emissions. SAE transactions, 90 (No 810345), 1410-1424.
Chambers, J. M., and Hastie, T. J., eds. (1992). Statistical Models in S. Wadsworth and Brooks, Pacific Grove, CA. pages 75, 222, 272-280, 331.
MathSoft, S-Plus software.


The ethanol data set is used to illustrate a number of techniques in Chambers and Hastie (1992), but especially to illustrate nonparametric and local regression.



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