This matrix gives discrepancies between light water nuclear power plants of two types, seven built on the site of an existing plant and 19 built on new sites. The discrepancies summarize differences in two covariates that are predictive of the cost of building a plant.
A matrix with 7 rows and 19 columns
The data appear in Cox, D.R. and Snell, E.J. (1981), Applied Statistics: Principles and Examples, p.82 (Chapman and Hall), and are due to W.E. Mooz.
Rosenbaum, P.R. (2002), Observational Studies, Second Edition, p.307 (Springer).