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 with 100 observations on the following 3 variables.
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 Statistics5, 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 Papers1 135–8.
U.S. Nautical Almanac Office. (See Table 24.)
Examples
require(stats); require(graphics)
michelson <- transform(morley,
Expt = factor(Expt), Run = factor(Run))
xtabs(~ Expt + Run, data = michelson) # 5 x 20 balanced (two-way)
plot(Speed ~ Expt, data = michelson,
main = "Speed of Light Data", xlab = "Experiment No.")
fm <- aov(Speed ~ Run + Expt, data = michelson)
summary(fm)
fm0 <- update(fm, . ~ . - Run)
anova(fm0, fm)
Results
R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
R is free software and comes with ABSOLUTELY NO WARRANTY.
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Type 'license()' or 'licence()' for distribution details.
R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.
Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.
> library(datasets)
> png(filename="/home/ddbj/snapshot/RGM3/R_rel/result/datasets/morley.Rd_%03d_medium.png", width=480, height=480)
> ### Name: morley
> ### Title: Michelson Speed of Light Data
> ### Aliases: morley
> ### Keywords: datasets
>
> ### ** Examples
>
> require(stats); require(graphics)
> michelson <- transform(morley,
+ Expt = factor(Expt), Run = factor(Run))
> xtabs(~ Expt + Run, data = michelson) # 5 x 20 balanced (two-way)
Run
Expt 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
4 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
5 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
> plot(Speed ~ Expt, data = michelson,
+ main = "Speed of Light Data", xlab = "Experiment No.")
> fm <- aov(Speed ~ Run + Expt, data = michelson)
> summary(fm)
Df Sum Sq Mean Sq F value Pr(>F)
Run 19 113344 5965 1.105 0.36321
Expt 4 94514 23629 4.378 0.00307 **
Residuals 76 410166 5397
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
> fm0 <- update(fm, . ~ . - Run)
> anova(fm0, fm)
Analysis of Variance Table
Model 1: Speed ~ Expt
Model 2: Speed ~ Run + Expt
Res.Df RSS Df Sum of Sq F Pr(>F)
1 95 523510
2 76 410166 19 113344 1.1053 0.3632
>
>
>
>
>
> dev.off()
null device
1
>