THE AUTHOR PRESENTS THE SYNOPTIC-IDEAL MODEL OF DECISIONMAKING AS USUALLY NOT POSSIBLE, BECAUSE IT IS DIFFICULT TO ORDER OBJECTIVES IN A SYSTEM OF PRIORITIES. THE MODEL FAILS TO RECOGNIZE LIMITATIONS ON THE HUMAN MIND, AND THE MODEL REQUIRES FULL INFORMATION REGARDING BOTH DIRECT AND INDIRECT EFFECTS OF EACH POSSIBLE ALTERNATIVE. EVEN WITH THE AID OF COMPUTER SIMULATION, THE SYNOPTIC MODEL HAS NOT BEEN VERY WORKABLE. THE INCREMENTAL MODEL OF DECISIONMAKING IS MORE APPROPRIATE WHEN KNOWLEDGE IS LIMITED. UNDER EITHER MODEL, HOWEVER, THERE IS A NEED FOR 'BUYING' INFORMATION. THREE WAYS OF BUYING INFORMATION ARE DISCUSSED: MODELING, EVALUATION, AND SYSTEMATIC EXPERIMENTATION. TERMS ARE DEFINED, AND A QUESTION-RESPONSE TYPE DISCUSSION IS INCLUDED. (AUTHOR ABSTRACT)...TWH