[…] However, experienced SAS programmers know that PROC SGPLOT is not omnipotent. It can overlay only statements that are compatible with each other. To simplify the syntax of PROC SGPLOT, graphs are categorized into four plot types: basic plots, fit and confidence plots, distribution plots, and categorization plots. Each SGPLOT statement is "compatible" with certain other statements, and only compatible features can be overlaid in a single plot. For example, the DOT statement is a categorization statement and can be combined only with HBAR, HBARBASIC, and HLINE statements. In contrast, the SCATTER statement is a basic plot and can be combined with most plots (except for categorization plots). The REFLINE statement is super-compatible and can be overlaid on any plot (but you might need to specify the formatted values of a discrete axis). …