Edexcel GCSE Statistics key terms

The change in a value expressed as a percentage of its original value: $\frac{\text{new value}-\text{original value}}{\text{original value}}\times100$.

A composite bar chart in which each complete bar represents 100%, so segment sizes show proportions rather than original frequencies.

A unit used to describe the difference between two percentages. A rise from 4% to 7% is an increase of 3 percentage points.

A boundary value in ordered data corresponding to a specified percentage of the observations. For example, the 90th percentile marks the boundary below which approximately 90% of observations lie.

A pattern that repeats at regular intervals, such as the same ordering of roles within successive teams on a list.

A change in apparent size or shape caused by the viewing angle or apparent depth of a representation.

An estimate of population size calculated using $N = \frac{Mn}{m}$, where $M$ is the number marked and released, $n$ is the second sample size and $m$ is the number marked in the second sample.

A representation of frequencies using pictures or symbols, with a key stating the value of one full symbol.

A circle divided into sectors whose angles represent the proportions in different categories.

A small-scale trial of a questionnaire used to identify problems before the main survey.

An inactive treatment designed to resemble the active treatment, allowing participants’ experiences to be kept similar.

The complete group of people, objects or measurements being studied.

A numerical characteristic of a whole population, such as its mean or the proportion of its members with a particular characteristic.

A diagram showing the distribution of a population across age groups, usually with male and female populations represented on opposite sides.

An association in which larger values of one variable tend to occur with larger values of the other.

A distribution shape with a longer tail towards higher values, usually shown on the right.

An estimate of an unknown or future result based on a pattern in data.

Preparation of data before calculations or other analysis, including data cleaning.

A small-scale trial of an experiment used to identify problems with its design or procedure before the full experiment.

Data collected by, or specifically for, the person or organisation that will use it.

An action planned or taken before a problem occurs, intended to prevent it or reduce its effects.

A number from 0 to 1 describing how likely an event is. It can be used as the expected proportion of outcomes belonging to that event.

The fraction of a group with a particular characteristic: $\text{proportion}=\frac{\text{number with the characteristic}}{\text{total number in the group}}$.

Data recorded as categories rather than numerical measurements or counts, such as ice-cream flavours.

The process of checking that products meet required standards, including using regular samples to monitor a manufacturing process.

Numerical observations or measurements representing quantities, such as the number of pets or a person's height.

A set of questions used to collect data from respondents.

The required number of members to be selected from a particular group in quota sampling.