What is the purpose of a scatter diagram?

A scatter diagram is used to display and analyse the relationship between two numerical variables.

In more detail, a scatter diagram, also known as a scatter plot, is a type of graph that shows individual data points plotted on a two-dimensional plane. Each point represents a pair of values, one from each of the two variables being compared. For example, you might plot the height and weight of a group of people to see if there is a relationship between these two measurements.

The main purpose of a scatter diagram is to visually assess whether there is a correlation between the variables. Correlation refers to how one variable changes in relation to the other. If the points on the scatter diagram tend to form a pattern, such as a line or curve, it suggests that there is a relationship. If the points are scattered randomly with no discernible pattern, it indicates that there is little to no correlation.

Scatter diagrams can show different types of relationships: positive correlation (both variables increase together), negative correlation (one variable increases while the other decreases), or no correlation (no clear pattern). By examining the scatter diagram, you can also identify outliers, which are data points that do not fit the general pattern. These outliers can be important for understanding anomalies or errors in the data.

Overall, scatter diagrams are a valuable tool in statistics for exploring and understanding the relationships between variables, making them a fundamental part of data analysis in GCSE Maths.