Glossary

• ||: absolute value of (the number without regard to sign)
• !: factorial
• P: probability
• P(A): probability of event A
• P(A or B) or P(AUB): probability of event A or event B
• P(A and B) or P(AΠB): probability of both A and B
• P(A|B): conditional probability of event A, given that event B has occurred
• Ā: complement of event A
• E(x): Expected value of a random variable x
• nCr: n choose r (Number of combinations of n elements selected r at a time)
• ∑: capital sigma (sum of what follows)
• α: alpha (probability of Type I error or significance level)
• β: beta (probability of Type II error)
• μ: mu (population mean)
• σ: lowercase sigma (population standard deviation)
• σ2: sigma square (population variance)
• ρ: mu (population mean)
• X²: chi-square
• s: s (sample standard deviation)
• s²: s square (sample variance)
• X or Y : X bar or Y bar (sample mean)
• df: degrees of freedom
• X−X: X minus X bar (deviation of a score from the mean)
• CI or (1 - α): confidence interval
• coefficient: a numerical or constant quantity placed before and multiplying the variable in an algebraic expression.
• A confidence interval, in statistics, refers to the probability that a population parameter will fall between a set of values for a certain proportion of times. Analysts often use confidence intervals that contain either 95% or 99% of expected observations.