Stevens {alr4} | R Documentation |
This experiment was apparently done by S. S. Stevens and colleagues in March 1962, although the exact reference is lost. 10 subjects were played tones at each of 5 loudnesses, presumably in random order. Subjects were asked to draw a line on paper whose length matched the loudness of the tone. Each subject repeated each loudness 3 times, for a total of 30 trials per subject. The original data are lost; reported here is the mean of the 3 log-lengths for each loudness, the sd of the three log-lengths, and the number of replications, which is always 3.
data(Stevens)
A data frame with 50 observations on the following 5 variables.
subject
a factor with unique values for each subject
loudness
either 50, 60, 70, 80 or 90 db. Decibels are a logrithmic scale
y
a numeric vector giving the mean of the log-lengths of three lines drawn. Exponentiating these values would give the geometric mean of the three lengths in cm.
sd
a numeric vector, giving the sd of the three log lengths
n
a numeric vector, equal to the constant value 3
This is a classic example of a psychophysics experiment pioneered by S. S. Stevens. The basic idea is that the phychological response y to a physical stimulus x should be proportional to x to a power. Since both the response and the loudness are already in log-scale, linear fits should be expected.
These data were obtained in the early 1970s from the data library in the Harvard University Statistics Department.
Stevens, S. S. (1966). A metric for social consensus, Science, 151, 530-541, http://www.jstor.org/stable/1717034
head(Stevens)