Edexcel GCSE Statistics key terms

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

A graph showing paired values of two variables, with each point representing one pair.

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

The difference between an actual value and the trend-line value at the same time: $\text{actual value}-\text{trend-line value}$.

Data already collected by somebody else.

A part of a circle bounded by two radii and an arc. Its angle determines the proportion represented in a pie chart.

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 asymmetry of a data distribution: whether its shape stretches further towards higher or lower values.

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

A numerical measure of the direction and strength of association between the ranks of two paired sets of data, written $r_s$.

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 how spread out values are around their mean, measured in the same units as the data. Its symbol is $\sigma$.

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.