library(ctest)
x<-c(864,636,638,708,786,600,1320,750,594,750,864,636,638,708,786,600,1320,750,594)
y<-c(1014,684,810,990,840,978,1002,1110,1014,684,810,990,840,978,1002,1110,1014,684,810)
t.test(x,y=y,alternative="two.sided")
t.test(x,y=y,alternative="less")
t.test(x,y=y)
t.test(x,y=y,paired=TRUE)

t.test(1:10,y=c(7:20))      # P = .00001855
t.test(1:10,y=c(7:20, 200)) # P = .1245    -- NOT significant anymore

## Classical example: Student's sleep data
## plot(extra ~ group, data = sleep)
## Traditional interface
## with(sleep, t.test(extra[group == 1], extra[group == 2]))
## Formula interface
## t.test(extra ~ group, data = sleep)