D004. Ultrasonic measurements of stress in rails

The data file can be downloaded here:

This dataset originates from a nondestructive experiment that tested for stress in railways rails (Pinheiro and Bates 2000). The sampling consisted in randomly choosing six rails (rail) and testing each three times by measuring the time it takes for a given type of ultrasonic wave to travel the complete length of the rail (travel).

d004 <- read.table(here::here("data", "RAIL.txt"), header = TRUE)

rail	travel
1	55
1	53
1	54
2	26
2	37
2	32
3	78
3	91

Pinheiro, J., and D. Bates. 2000. Mixed-effects models in S and S-PLUS. Springer. 527 p.