lines = '1 22.8
2 10.2
3 20.8
4 27.0
5 19.2
6 9.0
7 14.2
8 19.8
9 14.5
10 14.8
11 23.5
12 31.0
13 19.5
14 26.2
15 26.5
16 25.2
17 24.5
18 23.8
19 27.8
20 22.0'
con = textConnection( lines )
DF = read.table( con, header=FALSE )
close(con)
colnames(DF) = c('Cage', 'Weight_Gain')

inds = DF$Cage <= 10
test = DF$Weight_Gain[inds]

inds = DF$Cage >= 11
control = DF$Weight_Gain[inds]