Statistics key terms

A list of the members of a population from which a sample can be selected.

A number by which a measurement is multiplied. For similar shapes, multiplying lengths by $k$ multiplies areas by $k^2$ and volumes by $k^3$.

A transformation that multiplies every data value by the same factor, including division by a non-zero number.

A graph showing pairs of numerical values as points, with the explanatory variable on the horizontal axis and the response variable on the vertical axis.

A pattern of higher and lower values that repeats at particular times each year.

A regularly repeating effect in data collected over time. At a particular point, it is calculated as actual value minus trend value.

Existing data collected by somebody else and reused in an investigation.

A part of a circle bounded by two radii and an arc.

A systematic tendency for a selection method to favour some members or types of member over others.

A question about a personal or potentially embarrassing matter that respondents may be unwilling to answer honestly, or at all.

The potential for a topic or question to cause discomfort or distress, making people reluctant to discuss it.

A collection of items satisfying a stated condition.

A sample selected by a random method so that every member of the population has the same likelihood of inclusion.

A sampling method in which members are selected by chance, with every member of the population having an equal probability of selection.

A model of a real situation or process from which data can be generated to investigate possible outcomes.

An asymmetrical distribution in which values extend further on one side than the other.

The lack of symmetry in a distribution, described by the direction in which its tail extends.

Identifying where information or data came from so that its origin can be checked and its creator receives credit.

A measure of the strength and direction of the relationship between two variables using their ranks rather than their original values. It measures how consistently one variable increases or decreases as the other increases.

Software that organises information in rows and columns of cells and can use formulas to calculate results and generate charts.

A calculation entered into a spreadsheet cell, usually beginning with an equals sign, which can use values from other cells.

An apparent association between variables that does not represent a direct causal link between them, for example because both are influenced by a shared background factor.

A fixed reference width used to scale every histogram height. Frequency per standard class width equals frequency density multiplied by this reference width.

A measure of spread about the mean, calculated by taking the square root of the mean of the squared deviations from the mean.

A rate calculated by applying a population’s group-specific rates to a common standard population, allowing fairer comparisons between populations with different group proportions.

A value showing how many standard deviations a raw value lies above or below its own data set's mean, calculated using $\frac{x-\mu}{\sigma}$.

A reference population used to make comparisons on a common basis. In the calculations here, its age-group numbers total 1000.

A process for investigating questions using data: plan, collect data, process and represent it, interpret results, and evaluate the investigation. Stages can be repeated to improve the investigation.

A mathematical representation used to describe a pattern in data and estimate probabilities; a normal model represents data using a normal distribution.

A display of numerical data in which each value is split into a stem and a leaf, retaining the individual values.