3.8 Using Scatter Plots to Display Relationships between Numeric Variables

Scatter plots are preferred when looking at the relationship between two numeric variables. The SGPLOT procedure is the tool for this display. Are you seeing a pattern at this point? PROC SGPLOT is the statistical graphics procedure that accommodates most of the basic displays that you construct in a data analysis. More details about PROC SGPLOT and other statistical graphics procedures are provided in Chapter 6. Go ahead and jump to Chapter 6 if you are feeling a bit impatient. These procedures are a very cool addition to SAS 9.2 and it is well worth your time to explore their use.

The simple example in Display 3.18 produces three plots. The first plot shows the total number of young produced in three broods (total) versus nitrofen concentration (conc) where the value of the cbrood variable is used as a group variable that yields a different plotting symbol. (See Display 3.19.) The second plot shows the brood-specific counts as a function of nitrofen concentration. (See Display 3.20.) The third plot will be discussed in a moment.