Data Point

A data point is a single value plotted at one position on a chart — the smallest unit of data the chart displays.

Everything a chart shows is built up from data points. On a scatter plot a point is a literal dot; on a line chart it is one vertex the line passes through; on a bar chart it is the value the top of a bar marks. Each point pairs a location (which category or time) with a magnitude (how much), and reading a point means recovering both of those facts from its position.

How a data point works

A data point's position is set by the chart's axes. On a two-axis chart it carries two coordinates: where it sits along the horizontal axis and where along the vertical. Gridlines help you trace those positions back to numbers. Points that belong to the same variable are grouped into a data series and share a colour, so an individual point is read both on its own and as part of its series.

A concrete example

On a line chart of daily temperature, the point above "Wednesday" sitting level with the 18° gridline is a single data point: it states that Wednesday's temperature was 18 degrees. The line is simply many such points joined in order. Pick any one, drop straight down to read the day off the horizontal axis and straight across to read the value off the vertical axis, and you have decoded that point completely.

Related terms

A group of related data points forms a data series; a point's position is fixed by the axes and read with the help of gridlines. A point that sits far from the rest is an outlier. Individual points are most prominent in the scatter plot guide.