Standard Normal

Single Mean

s known

data i.i.d. normal

t-Distribution

(ν degrees freedom)

Single Mean

s unknown

n ≡ n − 1

data i.i.d. normal

Standard Normal

Two Means

s's known

data i.i.d. normal

t-Distribution (approx)

(ν degrees freedom)

Two Means

s's unknown

data i.i.d. normal,

distribution is approx

c2-Distribution

(ν degrees freedom)

One Variance

s known

n ≡ n − 1

data i.i.d. normal

F-Distribution

(ν1, n2 degrees freedom)

Two Variances

s's unknown

n1 ≡ n1 − 1

n2 ≡ n2 − 1

data i.i.d. normal