Rail: Evaluation of Stress in Railway Rails

In MEMSS: Data Sets from Mixed-Effects Models in S

Description

The Rail data frame has 18 rows and 2 columns.

Format

This data frame contains the following columns:

Rail

an ordered factor identifying the rail on which the measurement was made.

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.

Details

Devore (2000, Example 10.10, p. 427) cites data from an article in Materials Evaluation on “a study of travel time for a certain type of wave that results from longitudinal stress of rails used for railroad track.”

Source

Pinheiro, J. C. and Bates, D. M. (2000), Mixed-Effects Models in S and S-PLUS, Springer, New York. (Appendix A.26)

Devore, J. L. (2000), Probability and Statistics for Engineering and the Sciences (5th ed), Duxbury, Boston, MA.

Examples

str(Rail)
(fm1 <- lmer(travel ~ 1 | Rail, Rail))

Example output

Loading required package: lme4
Loading required package: Matrix

Attaching package: 'MEMSS'

The following objects are masked from 'package:datasets':

    CO2, Orange, Theoph

'data.frame':	18 obs. of  2 variables:
 $ Rail  : Factor w/ 6 levels "A","B","C","D",..: 1 1 1 2 2 2 3 3 3 4 ...
 $ travel: num  55 53 54 26 37 32 78 91 85 92 ...
Linear mixed model fit by REML ['lmerMod']
Formula: travel ~ 1 | Rail
   Data: Rail
REML criterion at convergence: 122.177
Random effects:
 Groups   Name        Std.Dev.
 Rail     (Intercept) 24.806  
 Residual              4.021  
Number of obs: 18, groups:  Rail, 6
Fixed Effects:
(Intercept)  
       66.5  

MEMSS documentation built on May 2, 2019, 1:05 p.m.