waterfilter {ANOM}

Comparison of Water Filters

Description

Filtering performances of seven brands of water filters, measured as the number of bacterial colonies growing on each device.

Usage

data(waterfilter)

Format

A data frame with 20 observations on the following 2 variables.

brand

A factor with 7 levels giving the brands of water filters.

colonies

A numeric vector giving the number of bacterial colonies found on each filter.

Details

A high number of bacterial colonies on a filter corresponds to good performance of this particular device. Note that the dataset is unbalanced (n=2 for brands 4 and 7, n=3 for all other brands).

Source

Hsu, J. C. (1984) Ranking and selection and multiple comparisons with the best. In: Santner, T. J. and Tamhane, A. C. (Editors) Design of Experiments: Ranking and Selection (Essays in Honor of Robert E. Bechhofer). Marcel Dekker, New York, NY, pp. 23–33.

References

Westfall, P. H., Tobias, R. D., Wolfinger, R. D. (2011) Multiple Comparisons and Multiple Tests Using SAS, Second Edition. SAS Institute Inc., Cary, NC, pp. 592–593.

Examples

data(waterfilter)
str(waterfilter)