Plane Answers to Complex Questions: Theory of Linear Models

“look ahead” from the current observation to the next one, without actually processing it, by using multiple SET statements and the FIRSTOBS option. Unfortunately, the clinical study relegates the PROC FORMAT statements to the appendix. Because the author does not stress that this information is pertinent to the discussion, it might be overlooked. By altering the previous convention of putting everything needed within the chapter, the reader who unwittingly bypasses the appendix references could easily become confused. The ozone study introduces the INTCK function to simplify time and date processing and the MOD function to create group indexes. The library study uses the _TYPE_ variable to conveniently generate categories for PROC CHART and introduces the attractive tabular output format of PROC TABULATE. Chapter 12 “Useful Macros,” the crown jewel of the book, provides a summation of all of the functions, detailing their execution as compact macros code. It illustrates automatic differencing between successive observations and uses the %SYSFUNC and TRANWRD functions to automate variable preŽ xing and sufŽ xing. I highly recommend this book to its target audience of SAS programmers and data analysts. It speaks to all levels of programming ability.