Reasons for the trend toward null findings in research on Type A behavior.

The findings of many studies conducted before 1978 suggest that Type A behavior (TAB) contributes to the development of coronary heart disease (CHD) and this research suggests that TAB, as assessed by the structured interview, is associated with CHD.

Abstract

The findings of many studies conducted before 1978 suggest that Type A behavior (TAB) contributes to the development of coronary heart disease (CHD). In contrast, many recent studies have found no association between these variables. Through meta-analysis, several reasons for null findings are identified. First, a type of range restriction bias, disease-based spectrum (DBS) bias, produced many null findings. A study is vulnerable to DBS bias when researchers select only high-risk or diseased Ss for study. Second, self-report measures of TAB were often associated with null findings. Finally, null results were found for all studies that used fatal myocardial infarction as a disease criterion. In addition to identifying the reasons for null findings, this research suggests that TAB, as assessed by the structured interview, is associated with CHD. More Type As (70%) were found in diseased populations of middle-aged men than in healthy populations of middle-aged men (46%).