QQ plot

A QQ plot, or quantile-quantile plot, is a graph used to compare two sets of data to see if they come from similar distributions. It plots their quantiles (values at specific points) against each other. If the points fall roughly along a straight line, it suggests the data sets have similar spread and shape. It’s often used to check if a dataset follows a normal (bell-shaped) distribution, making it a useful tool in statistics for assessing data assumptions before analysis.