Statistical notation


The null hypothesis is represented by H and a zero and the alternative hypothesis by H and a one:



The x-bar refers to the symbol (or expression) used to represent the sample mean, which is used as an estimation of the population mean. An x with a horizontal line above it represents the mean of x, a y with a horizontal line above the mean of y, etc. The population mean is defined by a ‘mu’ symbol.



Standard deviation




The population size, or number of observations, in an experiment is known as n.




P(A) represents the probability of ‘A’ happening e.g. on the toss of a coin P(Heads)=0.5.


P(A and B) is the syntax for a joint probability, that both events occur. P(A|B) represents a conditional probability, meaning the probability that A occurs given B.


Pr() is sometimes used rather than P().




The correlation coefficient is commonly referred to as r.