Decomposition can harm the accuracy of behavioural frequency reports

In survey research, the use of decomposition can lead to pronounced reporti ng errors as seen by overreporting and overall reporting error. A total of 87 subjects answered either decomposed or undecomposed questions concerning telephone calls made by them while at work. The questionnaire conditions V aried the length of the reference period (I week or 6 months), and the type of call (local or long-distance). Decomposition conditions introduced eith er spatial or temporal cues. In all comparisons, decomposed questions incre ased overreporting bias relative to undecomposed questions. In addition, un decomposed questions with a I-week reference period led to increased overre porting bias in comparison to undecomposed/6-month questions. Results are c onsistent with a category split estimation model in which smaller categorie s are predicted to lead to overreporting, and larger categories to underrep orting. Decomposition is not recommended for gaining retrospective reports of non-distinctive, frequent events. Copyright (C) 2000 John Wiley & Sons, Ltd.