Scatter plots are used to analyze the relationship between two sets of data by plotting points on a graph without connecting them. Points that form a positive sloping pattern from bottom left to top right indicate a direct relationship, while an inverse pattern shows an indirect relationship, and no pattern means no relationship exists between the variables. The stat key in a graphing calculator can be used to choose the lists of data for the x and y axes and determine the window ranges to plot scatter plot graphs for analysis.