# This program demonstrates the power of t.test command
# t.test can do almost all important tasks related to normal
# distribution for standard statistics courses.
# Created by C. Andy Tsao, 060516

# Just a selected list of what t.test can do
# 1. One population hypothesis tests for population mean
#                confidence intervals
# 2. For two normal populations, it can be used to perform
# two-sample t-test with or without equal variances
# and paired t-test.
# 3. Since t_df --> z as df -> \infty, t.test can also servered as a tool
# for calculating p-value for asympotic test and asymptotic CI.

x<-rnorm(10)
y<-rnorm(12)+2

t.test(x,y)
t.test(x,y,var.equal=TRUE)
t.test(x,conf.level = 0.9,alternative = "less")