T distribution

• generalizes the standard normal distribution
• symmetric about 0
• bell shape
• unknown variances
• uses degrees of freedom
• t distribution is symmetric about 0
  • Mean = Median = 0
• has a lower peak then the SND and more area in the tails
  • 
• the variance of the t distribution is $\frac{df}{df-2}$ for degrees of freedom > 2
  • degrees of freedom = $n-1$
  • the t distribution tends toward the SND as $df\to \mathrm{\infty }$
• $df=n-1$