Format
A data frame with 20 observations on the following 2 variables.
BRAND- a factor with levels
BRAND.A BRAND.B STRENGTH- a numeric vector
Source
Phillips, A., Jeffries, R., Schneider, J, and Frankoski, S. (1997) Using
Repeatability and Reproducibility Studies to Evaluate a Destructive Test Method.
Quality Engineering, 10, pp. 283-290.