Data from Kay and Heer (2016), used for testing.
For more details, see Kay and Heer (2016) or the github repository describing the analysis: https://github.com/mjskay/ranking-correlation. The original experiment (but not this analysis of it) is described in Harrison et al. (2014).
Kay, Matthew, and Jeffrey Heer. "Beyond weber's law: A second look at ranking visualizations of correlation." IEEE transactions on visualization and computer graphics 22.1 (2016): 469-478.
Harrison, Lane, Fumeng Yang, Steven Franconeri, and Remco Chang. "Ranking visualizations of correlation using weber's law." IEEE transactions on visualization and computer graphics 20.12 (2014): 1943-1952.