The
ethanol data frame records 88 measurements (rows) for three
variables (columns)
NOx ,
C , and
E from an experiment in which
ethanol was burned in a single cylinder automobile test engine.
The
gas data frame records 22 measurements of
NOx and
E from a
similar experiment involving gasoline in place of ethanol.
Brinkman, N.D. (1981) Ethanol Fuel---A single-cylinder Engine Study of
Efficiency and Exhaust Emissions. SAE transactions
Vol. 90, No 810345, pp. 1410--1424.
John M. Chambers and Trevor J. Hastie, (eds.) Statistical Models in S,
Wadsworth and Brooks, Pacific Grove, CA 1992, pp. 75, 222, 272--280, 331.
eth1 <- gam(NOx ~ C + lo(E, degree = 2), data = ethanol)