+----------+-------------------+
| morley   | R Documentation   |
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Michelson Speed of Light Data
-----------------------------

Description
~~~~~~~~~~~

A classical data of Michelson (but not this one with Morley) on
measurements done in 1879 on the speed of light. The data consists of
five experiments, each consisting of 20 consecutive ‘runs’. The response
is the speed of light measurement, suitably coded (km/sec, with
``299000`` subtracted).

Usage
~~~~~

::

    morley

Format
~~~~~~

A data frame contains the following components:

``Expt``
    The experiment number, from 1 to 5.

``Run``
    The run number within each experiment.

``Speed``
    Speed-of-light measurement.

Details
~~~~~~~

The data is here viewed as a randomized block experiment with
‘experiment’ and ‘run’ as the factors. ‘run’ may also be considered a
quantitative variate to account for linear (or polynomial) changes in
the measurement over the course of a single experiment.

Note
~~~~

This is the same dataset as ``michelson`` in package MASS.

Source
~~~~~~

A. J. Weekes (1986) *A Genstat Primer*. London: Edward Arnold.

S. M. Stigler (1977) Do robust estimators work with real data? *Annals
of Statistics* **5**, 1055–1098. (See Table 6.)

A. A. Michelson (1882) Experimental determination of the velocity of
light made at the United States Naval Academy, Annapolis. *Astronomic
Papers* **1** 135–8. U.S. Nautical Almanac Office. (See Table 24.)

Examples
~~~~~~~~

::

    require(stats); require(graphics)
    morley$Expt <- factor(morley$Expt)
    morley$Run <- factor(morley$Run)

    xtabs(~ Expt + Run, data = morley)# 5 x 20 balanced (two-way)
    plot(Speed ~ Expt, data = morley,
         main = "Speed of Light Data", xlab = "Experiment No.")
    fm <- aov(Speed ~ Run + Expt, data = morley)
    summary(fm)
    fm0 <- update(fm, . ~ . - Run)
    anova(fm0, fm)

