Example 1.2.1: comparing three doses of a drug

Packed cell volume (PCV, %) of trypanosome-infected animals before and one month after a low, medium or high dose of Berenil: a completely randomised design (Table 1.2.1 and Appendix A of the book).

Usage

ex121

Format

A data frame with 14 rows and 5 variables:

animals

animal number within its dose group.

dose

dose: H (high), L (low) or M (medium).

PCV1

PCV at treatment.

PCV2

PCV one month after treatment.

PCVdiff

change in PCV, PCV2 - PCV1.

Source

Duchateau, L., Janssen, P. and Rowlands, G. J. (1998). Linear Mixed Models. An Introduction with Applications in Veterinary Research. International Livestock Research Institute, Nairobi. Appendix A.

See also

Examp2.2.1.7

Other VetResearchLMM data: ex122, ex123, ex124, ex125, ex126, ex127, ex31, ex32, ex33

Examples

str(ex121)
#> 'data.frame':	14 obs. of  5 variables:
#>  $ animals: int  1 2 3 4 5 1 2 3 4 1 ...
#>  $ dose   : Factor w/ 3 levels "H","L","M": 2 2 2 2 2 3 3 3 3 1 ...
#>  $ PCV1   : num  17.4 18.7 15.8 16.4 16.6 16.8 17.3 17.5 15.2 18 ...
#>  $ PCV2   : num  19.3 18.9 19.2 19.9 17.8 22.6 19.7 20.2 19.5 25.7 ...
#>  $ PCVdiff: num  1.9 0.2 3.4 3.6 1.1 5.9 2.4 2.7 4.3 7.7 ...
tapply(X = ex121$PCVdiff, INDEX = ex121$dose, FUN = mean)
#>     H     L     M 
#> 7.620 2.040 3.825