Three-factor experiment comparing pollution-filter noise for two filters, three sizes of cars, and two sides of the car.
Usage
auto.noise
Format
A data frame with 36 observations on the following 4 variables.
noise
Noise level in decibels - a numeric vector.
size
The size of the vehicle - an ordered factor with levels S, M, L.
type
Type of anti-pollution filter - a factor with levels Std and Octel
side
The side of the car where measurement was taken – a factor with levels L and R.
Details
The data are from a statement by Texaco, Inc., to the Air and Water Pollution
Subcommittee of the Senate Public Works Committee on June 26, 1973.
Mr. John McKinley, President of Texaco, cited an automobile filter developed
by Associated Octel Company as effective in reducing pollution. However,
questions had been raised about the effects of filters on vehicle performance,
fuel consumption, exhaust gas back pressure, and silencing. On the last
question, he referred to the data included here as evidence that the silencing
properties of the Octel filter were at least equal to those of standard silencers.
Source
The dataset was imported from the Data and Story Library - http://lib.stat.cmu.edu/DASL/Datafiles/airpullutionfiltersdat.html (sic). However,
the factor levels were assigned meaningful names, and the observations were sorted
in random order as if this were the run order of the experiment.
References
A.Y. Lewin and M.F. Shakun (1976) Policy Sciences: Methodology and Cases. Pergammon Press. p.313.
Examples
require(lsmeans)
noise.lm <- lm(noise ~ size * type * side, data = auto.noise)
# Interaction plot of predictions
lsmip(noise.lm, type ~ size | side)
# Confidence intervals
plot(lsmeans(noise.lm, ~ size | side*type))