(1) A graphical technique to analyze the relationship between two variables. Two sets of data are plotted on a graph, with the y-axis being used for the variable to be predicted and the x-axis being used for the variable to make the prediction. The graph will show possible relationships (although two variables might appear to be related, they might not be; those who know most about the variables must make that evaluation). One of the "seven tools of quality".
(2) A scatter plot used to examine the relationships between variables.
(3) To identify relationships between two process variables. Used when the team thinks that one variable is dependent on another to confirm that two variables have a relationship. If investigating dependence, set the independent variable on the x-axis and the dependent variable on the y-axis.