1 sample T-test

Default command line for 1 sample T-test

t.test(x, mu = 0, alternative = "two.sided")

x – numeric vector containing data

mu – theoretical mean

alternative = “two.sided” “greater” “less”

Example: A plant scientist would like to determine if 
the heights of maize plants are different from the 
average mean height of 180 cm. He sampled randomly from 16 plants.(α = 0.05)

1 sample T-test

x<-c(186,180,176,177,178,181,180,182,183,180,181,
     180,180,183,185,181)
t.test(x, mu = 180, alternative = "two.sided")

## 
##  One Sample t-test
## 
## data:  x
## t = 1.2317, df = 15, p-value = 0.237
## alternative hypothesis: true mean is not equal to 180
## 95 percent confidence interval:
##  179.4065 182.2185
## sample estimates:
## mean of x 
##  180.8125

To change the confidence level, add conf.level =

x<-c(186,180,176,177,178,181,180,182,183,180,181,
     180,180,183,185,181)
t.test(x, mu = 180, alternative = "two.sided",conf.level=0.99)

## 
##  One Sample t-test
## 
## data:  x
## t = 1.2317, df = 15, p-value = 0.237
## alternative hypothesis: true mean is not equal to 180
## 99 percent confidence interval:
##  178.8687 182.7563
## sample estimates:
## mean of x 
##  180.8125