patterson.switchback {agridat} R Documentation

## Switchback experiment on dairy cattle, milk yield for 4 treatments

### Description

Switchback experiment on dairy cattle, milk yield for 4 treatments

### Usage

`data("patterson.switchback")`

### Format

A data frame with 36 observations on the following 4 variables.

`y`

response, milk FCM

`trt`

treatment factor, 4 levels

`period`

period factor, 3 levls

`cow`

cow factor, 12 levels

### Details

There are three periods. Each cow is assigned to one treatment cycle like T1-T2-T1, where T1 is the treatment in period P1 and P3, and T2 is the treatment in period P2.

There are four treatments.

All 4*3 = 12 treatment cycles are represented.

Data were extracted from Lowry, page 70.

### Source

Patterson, H.D. and Lucas, H.L. 1962. Change-over designs. Technical Bulletin 147, North Carolina Agricultural Experimental Station.

### References

Lowry, S.R. 1989. Statistical design and analysis of dairy nutrition experiments to improve detection of milk response differences. Proceedings of the Conference on Applied Statistics in Agriculture, 1989. https://newprairiepress.org/agstatconference/1989/proceedings/7/

### Examples

```## Not run:

library(agridat)
data(patterson.switchback)
dat <- patterson.switchback

# Create groupings for first treatment, second treatment
datp1 <- subset(dat, period=="P1")
datp2 <- subset(dat, period=="P2")
dat\$p1trt <- datp1\$trt[match(dat\$cow, datp1\$cow)]
dat\$p2trt <- datp2\$trt[match(dat\$cow, datp2\$cow)]

libs(latticeExtra)
useOuterStrips(xyplot(y ~ period|p1trt*p2trt, data=dat,
group=cow, type=c('l','r'),
auto.key=list(columns=5),
main="patterson.switchback",
xlab="First/Third period treatment",
ylab="Second period treatment"))

# Create a numeric period variable
dat\$per <- as.numeric(substring(dat\$period,2))

# Need to use 'terms' to preserve the order of the model terms
m1 <- aov(terms(y ~ cow + per:cow + period + trt, keep.order=TRUE), data=dat)
anova(m1) # Match table 2 of Lowry
## Analysis of Variance Table
##           Df Sum Sq Mean Sq F value    Pr(>F)
## cow       11 3466.0 315.091 57.1773 2.258e-06 ***
## cow:per   12  953.5  79.455 14.4182 0.0004017 ***
## period     1   19.7  19.740  3.5821 0.0950382 .
## trt        3   58.3  19.418  3.5237 0.0685092 .
## Residuals  8   44.1   5.511

## End(Not run)
```

[Package agridat version 1.18 Index]