These are the symbols that will be used in this course. They are ordered approximately related to order of modules where the symbol was introduced.

Symbol Definition
N
Population size. [generally unknown]
n
Sample size.
xi
Value of the X variable for the ith individual.
$$\bar{\textrm{x}}$$
Sample mean (average) of the X variable.
s
Sample standard deviation.
s2
Sample variance.
M
The sample median. [rarely used]
Q1
First quartile.
Q3
Third quartile.
IQR
Interquartile range (Q3-Q1).
μ
Population mean.
σ
Population standard deviation.
X~N(μ,σ)
The variable X is normally distributed with a mean of μ and standard deviation of σ.
N(0,1)
Standard normal distribution.
c
The number of columns in a two-way frequency table.
r
The sample correlation coefficient OR number of rows in a two-way frequency table.
r2
The coefficient of determination.
$$\hat{\textrm{y}}_{\textrm{i}}$$
Predicted value of the response variable (in regression).
Residual sum-of-squares.
H0
The null hypothesis.
HA
The alternative hypothesis.
α
The rejection criterion OR probability of making a Type I error.
β
The probability of making a Type II error.
C
The level of confidence for a confidence region.
Z
A variable that follows a N(0,1) OR the test statistic in a one-sample Z-test.
μ0
Specific value of μ in the H0 of 1-Sample Z- and t-Tests.
t
A variable that follows a t-distribution OR the test statistic in t-tests.
sp2
Pooled sample variance in a 2-Sample t-Test.
σ2
Population variance.
df
Degrees-of-freedom.
χ2
A variable that follows a chi-square distribution OR the test statistic in chi-square tests.
p
Population proportion of successes.
$$\hat{\textrm{p}}$$
Sample proportion of successes.