Scatter plots can be useful to display possible relationships between two variables. Once a pattern is recognized, fitting a function to the data and then recognizing how well the function represents the relationship in the data can support your intuition about relationships between variables by providing some values to describe the relationship. The best-fit line, for example, can be used to predict the value of one variable based on the value of a second variable. Although technology can aid in finding best-fit lines and evaluating the strength of a line’s fit, human understanding of the variables and of how the data were collected is still required to determine whether the relationship is merely a relationship or whether there is a causal relationship.