Greek Letters in Statistics
Letter

Name 
Statistical Reference 
a 
alpha 
lower case

Significance, i.e. the probability of a type I error.
Confidence
is (1  a)⋅100% .

b 
beta  lower case

Consumer's risk, i.e. the probability of a type II error.

m 
mu  lower case

Population mean.

s 
sigma
 lower case

Population standard deviation.

S

sigma
 upper case

Tells
the reader to sum what follows it in a formula. 
r 
rho  lower case

Population correlation coefficient.

q 
theta
 lower case

Population proportion (in some texts).

c^{ 2} 
lower
case chi squared (Greek
letter squared) 
A type of probability distribution used in testing hypotheses involving
more than two possible outcomes.
