4*7

# read this:
#     ex1 gets scan ....
ex1 <- scan('http://math.uttyler.edu/nathan/classes/statistics/data/example1.data')
ex1

mean(ex1)
summary(ex1)
sd(ex1)

# Let's do a confidence interval the hard way
mean(ex1) - 1.96*sd(ex1)/sqrt(30)            #really should use t here but 
mean(ex1) + 1.96*sd(ex1)/sqrt(length(ex1))   #this should be close

# Let's do a confidence interval the easy way
t.test(ex1)


#	One Sample t-test
#
#data:  ex1 
#t = 10.3287, df = 29, p-value = 3.152e-11
#alternative hypothesis: true mean is not equal to 0 
#95 percent confidence interval:
#  7.77451 11.61362 
#sample estimates:
#mean of x 
# 9.694066 

t.test(ex1,conf.level=.99)



ex2 <-
  read.table('http://math.uttyler.edu/nathan/classes/statistics/data/example2.data',header=TRUE)

summary(ex2)
t.test(ex2)

ex3 <- 
  read.table('http://math.uttyler.edu/nathan/classes/statistics/data/example3.data',header=TRUE)

ex3[1:5,]

v1   # you get an error!!!

ex3$v1  # the 'v1' column of ex3
t.test(ex3$v1)

t.test(ex3$v1)$conf.int


q