holtsmark.timothy.uniformity {agridat} | R Documentation

## Uniformity trial of timothy

### Description

Uniformity trial of timothy hay circa 1905

### Usage

    data("holtsmark.timothy.uniformity")

### Format

A data frame with 240 observations on the following 3 variables.

`row`

  row

`col`

  column

`yield`

  yield per plot, kg

### Details

Field width: 40 plots * 5 m = 200 m.

Field length: 6 plots * 5 m = 30 m

Holtsmark & Larsen used this trial to compare standard deviations of different sized plots (combined from smaller plots).

### Source

Holtsmark, G and Larsen, BR (1905). Om Muligheder for at indskraenke de Fejl, som ved Markforsog betinges af Jordens Uensartethed. Tidsskrift for Landbrugets Planteavl. 12, 330-351. (In Danish) https://books.google.com/books?id=MdM0AQAAMAAJ&pg=PA330 http://dca.au.dk/publikationer/historiske/planteavl/

Uber die Fehler, welche bei Feldversuchen, durch die Ungleichartigkeit des Bodens bedingt werden. Die Landwirtschaftlichen Versuchs-Stationen, 65, 1–22. (In German) https://books.google.com/books?id=eXA2AQAAMAAJ&pg=PA1

### References

Theodor Roemer (1920). Der Feldversuch.

### Examples

    data(holtsmark.timothy.uniformity)
    dat <- holtsmark.timothy.uniformity

    # Define diagonal 'check' plots like Holtsmark does
    dat <- transform(dat,
                     check = ifelse(floor((row+col)/3)==(row+col)/3, "C", ""))

    if(require(desplot)){
      desplot(yield ~ col*row, data=dat, flip=TRUE, text=check, show.key=FALSE,
              aspect=30/200, # true aspect
              main="holtsmark.timothy.uniformity")
    }

    sd(dat$yield) # 2.92 matches Holtsmark p. 348

[Package agridat version 1.16 Index]