Glossary

Table 8: Glossary Week 7
Term Description
generalisability The ability to apply the findings made on the basis of a representative sample to the population
non-probability sampling In non-probability sampling not every unit has the same probability of being sampled
normal distribution The Normal Distribution is a bell-shaped probability distribution which is symmetrical around the mean
parameter A parameter is the value a statistic would assume in the long run. It is also called the Expected Value
population Collection of all cases which possess certain pre-defined characteristics
population distribution The probability distribution of the population
probability Refers to how many times out of a total number of cases a particular event occurs. We can also see it as the chance of a particular event occurring
probability sampling In probability sampling all units have the same probability of entering the sample. In addition, all possible combinations of n cases must have the same probability to be selected
representative sample A sample which contains all characteristic of the population in accurate proportions
sample A sub-group of the population
sample distribution The probability distribution of a sample
sampling The process of selecting sampling units from the population
sampling distribution The probability distribution of a sample statistics, such as the mean. It can be derived from repeated sampling, or by estimation
sampling error The extent to which the mean of the population and the mean of the sample differ from one another
sampling method The way the sample is created
standard error The standard deviation of the sampling distribution. It is defined as:\[\begin{equation*}\sigma_{\bar{y}} = \frac{\sigma}{\sqrt{n}}\end{equation*}\]
z-score The z-score, sometimes also referred to as z-value, expresses in units of standard deviation how far an observation of interest falls away from the mean. It is defined as \[\begin{equation*}z = \frac{\text{observation} - \text{mean}}{\text{standard deviation}}=\frac{y-\mu}{\sigma}\end{equation*}\]