### Hypotheses

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

### Mean

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

### Population

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

### Probability

**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()**.

### Correlation

The correlation coefficient is commonly referred to as **r**.