Barley: Barley data from Preece (1982, Table 1)

In PairedData: Paired Data Analysis

Description

This dataset presents 12 paired data corresponding to the yields of Glabron and Velvet Barley, grown on different farms. The values from farm 12 are quite different.

Usage

data(Barley)

Format

A dataframe with 17 rows and 3 columns:

[,1]	Farm	factor
[,2]	Glabron	numeric	yields (bushels per acre)
[,3]	Velvet	numeric	yields

Source

Leonard, W.H. & Clark, A.G. (1939) Field Plot Techniques. Burgess: Minneapolis.

References

Preece D.A. (1982) t is for trouble (and textbooks): a critique of some examples of the paired-samples t-test. The Statistician, 31 (2), 169-195.

Examples

data(Barley)

# Visualizing a clear outlier
with(Barley,plot(paired(Glabron,Velvet),type="BA"))

# Results form the paired t test and paired Yuen test are similar
with(Barley,t.test(paired(Glabron,Velvet)))
with(Barley,yuen.t.test(paired(Glabron,Velvet)))

# Nevertheless the outlier inflates the location (numerator) and
# scale (denominator) standard statictics for the difference
with(Barley,summary(paired(Glabron,Velvet)))

Example output

Loading required package: MASS
Loading required package: gld
Loading required package: mvtnorm
Loading required package: lattice
Loading required package: ggplot2

Attaching package: 'PairedData'

The following object is masked from 'package:base':

    summary


	Paired t-test

data:  Glabron and Velvet
t = 3.0133, df = 11, p-value = 0.0118
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
  1.594978 10.238355
sample estimates:
mean of the differences 
               5.916667 


	Paired Yuen test, trim=0.2

data:  Glabron and Velvet
t = 3.6354, df = 7, p-value = 0.008338
alternative hypothesis: true difference in trimmed means is not equal to 0
95 percent confidence interval:
 2.053657 9.696343
sample estimates:
trimmed mean of x - trimmed mean of y 
                                5.875 

$stat
             n      mean median    trim       sd  IQR (*) median ad (*)
Glabron (x) 12 48.333333   47.5 47.8750 7.302967 4.633062        4.4478
Velvet (y)  12 42.416667   41.5 42.0000 5.946096 4.818384        4.4478
x-y         12  5.916667    5.0  4.2500 6.801849 3.891772        4.4478
(x+y)/2     12 45.375000   46.0 45.4375 5.725243 3.335804        3.7065
            mean ad (*)    sd(w)  min  max
Glabron (x)    6.475456 4.671368 37.0 64.0
Velvet (y)     5.117699 5.159445 32.0 56.0
x-y            5.117699 4.031298  0.0 25.0
(x+y)/2        5.169921 3.936118 34.5 56.5

$cor
            cor      wcor
(x,y) 0.4884868 0.3356163

PairedData documentation built on May 1, 2019, 6:49 p.m.