Forty years of Out-of-Stock research - and shelves are still empty

This article examines 40 years of research conducted in the area of Out-of-Stocks (OOS). Two research streams originating from the Progressive Grocer (1968) study are reviewed. The first stream dealt with demand side issues and analysed consumer responses to OOS. The other dealt with supply side issues and analysed the extent and root causes of OOS situations as well as how to improve OOS. Four paradoxes are derived from the review and are discussed: 1) OOS rates largely seem to fall into an average level at about 7 to 8% despite 40 years of research; 2) only sparse attempts have been made to integrate the two research streams; 3) there is an emphasis on minimizing OOS rather than relying on basic trade-offs as addressed by Economic-Order-Quantity theory to optimize OOS levels; and 4) despite clear evidence of the store as the major contributor to OOS situations, the store has largely remained a 'black-box' in OOS research. Finally, the study suggests that OOS research can integrate the notions of the two streams by showing how the conditions for consumer responses can be translated into different degrees for costs of understocking taken from Economic-Order-Quantity theory. This will have important implications for the management of OOS.