Wheat {HistData} | R Documentation |
Playfair (1821) used a graph, showing parallel time-series of the price of wheat and the typical weekly wage for a "good mechanic" from 1570 to 1820 to argue that working men had never been as well-off in terms of purchasing power as they had become toward the end of this period.
His graph is a classic in the history of data visualization, but commits the sin of showing two non-commensurable Y variables on different axes. Scatterplots of wages vs. price or plots of ratios (e.g., wages/price) are in some ways better, but both of these ideas were unknown in 1821.
data(Wheat)
A data frame with 26 observations on the following 4 variables.
Year
Wheat
Wages
Monarch
Anne
Charles
Cromwell
Elizabet
George I
James I
James II
William
Playfair, W. (1821). Letter on our Agricultural Distresses, Their Causes and Remedies. London: W. Sams, 1821
Data values: digitized from http://www.math.yorku.ca/SCS/Gallery/images/playfair-wheat1.gif
Friendly, M. & Denis, D. (2005). The early origins and development of the scatterplot Journal of the History of the Behavioral Sciences, 41, 103-130.
data(Wheat) # trivial time series plot Play.ts <- ts(Wheat[,2:3], start=1570, end=1820, deltat=10) plot(Play.ts, plot.type="single", col=1:2)