What does the line of best fit represent in a scatter diagram?

The line of best fit represents the trend or relationship between two variables in a scatter diagram.

In more detail, a scatter diagram is a type of graph used to display values for two variables for a set of data. Each point on the graph represents an individual data point. The line of best fit, also known as a trend line, is a straight line that best represents the data on a scatter plot. It shows the general direction that the data points tend to follow.

To draw the line of best fit, you try to position it so that it has roughly equal numbers of points on either side and minimises the distances from the points to the line. This line helps to visualise any correlation between the variables. If the line slopes upwards from left to right, it indicates a positive correlation, meaning as one variable increases, the other tends to increase as well. Conversely, if the line slopes downwards, it indicates a negative correlation, meaning as one variable increases, the other tends to decrease.

The line of best fit is useful because it allows us to make predictions. For example, if you have data on hours studied and exam scores, the line of best fit can help predict the likely exam score for a given number of study hours. It simplifies complex data and makes it easier to understand the relationship between the variables. However, it's important to remember that the line of best fit is an approximation and may not perfectly predict individual outcomes.