Machines {lme4} | R Documentation

## Productivity Scores for Machines and Workers

### Description

The `Machines` data frame has 54 rows and 3 columns.

### Format

This data frame contains the following columns:

Worker
  an ordered factor giving the unique identifier for the worker.
Machine
  a factor with levels `A`, `B`, and `C` identifying the machine brand.
score
  a productivity score.

### Details

Data on an experiment to compare three brands of machines used in an industrial process are presented in Milliken and Johnson (p. 285, 1992). Six workers were chosen randomly among the employees of a factory to operate each machine three times. The response is an overall productivity score taking into account the number and quality of components produced.

### Source

Pinheiro, J. C. and Bates, D. M. (2000), Mixed-Effects Models in S and S-PLUS, Springer, New York. (Appendix A.14)

Milliken, G. A. and Johnson, D. E. (1992), Analysis of Messy Data, Volume I: Designed Experiments, Chapman and Hall, London.

### Examples

    data(Machines)

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