THE EFFECT OF INFERENCE ORDER AND EXPERIENCE-RELATED KNOWLEDGE ON DIAGNOSTIC CONJUNCTION PROBABILITIES

Ideally, a decision maker's diagnostic probability judgments should no t be affected by making predictive judgments before making diagnostic inferences. The purpose of this study is to investigate how experience -related knowledge and the inference presentation order affect a decis ion maker's diagnostic conjunction probability judgments. Specifically , when decision makers are asked to make diagnoses in different judgme nt domains with which they have different levels of experience, we exa mine how making predictions first affects their subsequent diagnostic judgments in a standard conjunction paradigm. Professional auditors wi th experience in the auditing domain and MBA students with little or n o auditing experience participated in the experiment. The results indi cate that when the task involves a domain with which people have exper ience, making predictions prior to diagnoses has a significant influen ce on their subsequent diagnostic conjunction probabilities. When audi tors made diagnoses in a familiar audit task situation, they were stro ngly influenced by whether or not they were asked to make predictions in advance. However, there was no influence of inference order on audi tors' diagnoses in a medical task, with which they do not have experie nce-related knowledge. Similarly, MBA students, having no experience-r elated knowledge in either audit or medical domains, were not affected by the inference order in making diagnoses. In the discussion of thes e exploratory results, we suggest that this inference order effect may be due to subjects' anchoring on the predictive probability and insuf ficiently adjusting it to yield the diagnostic probability judgment. ( C) 1994 Academic Press, Inc.