Glossary — Statistics

Average — a value that represents a typical result in a set of data.

Bar chart — a chart that uses separate bars to compare categories of data.

Biased sample — a sample chosen in a way that favours some members of the population.

Box plot — a diagram that shows the median, quartiles and extreme values of a data set.

Cumulative frequency — the running total of frequencies up to and including each value or group.

Data — information collected for a purpose.

Frequency — the number of times a value or category occurs.

Histogram — a chart for grouped continuous data where bar area represents frequency.

Interquartile range — the difference between the upper and lower quartiles; it measures the spread of the middle half of the data.

Line of best fit — a straight line drawn through a scatter graph to show the overall pattern.

Mean — the total of the values divided by how many values there are.

Median — the middle value when data values are arranged in order.

Mode — the value or category that occurs most often.

Outlier — a data value that lies far from the main group.

Pie chart — a circle chart divided into sectors to show how a total is split between categories.

Population — the whole group that a statistical investigation is about.

Primary data — data you collect yourself for a particular investigation.

Quartile — one of three values that divide ordered data into four equal groups.

Random sample — a sample chosen so each member of the population has an equal chance of selection.

Range — the difference between the largest and smallest values in a data set.

Sample — a smaller group chosen from a population to provide information about it.

Scatter graph — a graph that plots paired values to show how two variables are related.

Secondary data — data collected by someone else or for a different purpose.

Systematic sample — a sample chosen by taking members at regular intervals from an ordered list.

Time series — data collected at regular time intervals.

Correlation — a relationship between two variables shown by the pattern of points on a scatter graph.