###### R command for section 4.6

## Example 4.6-3
# before the short course
y = scan()
43 82 77 39 51 66 55 61 79 43

# after the short course
x = scan()
51 84 74 48 53 61 59 75 82 48

# one-sided paired t test
t.test(x, y, alternative="greater", paired=T)

# one-sided equal-variance t test
t.test(x, y, alternative="greater", var.equal=T)

# one-sided nonequal-variance t test
t.test(x, y, alternative="greater")


## read data from a file, if data file is in the working folder
data = read.table("example463.dat", head=T)
y = data$y
x = data$x
t.test(x, y, alternative="greater", paired=T)

## do t test step by step
w = x - y
wvar = var(w)    # sample variance of w
wbar = mean(w)   # sample mean of w
n = 10
tstat = wbar/sqrt(wvar/n)   # t statistic
pvalue = pt(tstat, df=n-1, lower.tail = F)




## check for other kinds of available test in R
??test