xmp10.10 {Devore6} | R Documentation

## data from Example 10.10

### Description

The `xmp10.10` data frame has 18 rows and 2 columns.

### Format

This data frame contains the following columns:

travel
  a numeric vector giving the travel time for ultrasonic head-waves in the rail (nanoseconds). The value given is the original travel time minus 36,100 nanoseconds.
Rail
  an ordered factor identifying the rail on which the measurement was made.

### Details

Data from a study of travel time for a certain type of wave that results from longitudinal stress of rails used for railroad track.

### Source

Devore, J. L. (2003), Probability and Statistics for Engineering and the Sciences (6th ed), Duxbury, Boston, MA.

Pinheiro, J. C. and Bates, D. M. (2003), Mixed-Effects Models in S and S-PLUS, Springer, New York. (Appendix A.26)

(1985), ``Zero-force travel-time parameters for ultrasonic head-waves in railroad rail'', Materials Evaluation, 854-858.

### Examples

    data(xmp10.10)
    xmp10.10$Rail <- factor(xmp10.10$Rail)
    boxplot(travel ~ Rail, xmp10.10, col = "lightgray",
      xlab = "Rail", ylab = "Zero-force travel time (microsec)",
      main = "Travel times in rails, from example 10.10")
    fm1 <- lm(travel ~ Rail, data = xmp10.10)
    anova(fm1)

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