AbstractThe retrieval performance of a technique for automated indexing using a controlled vocabulary (machine‐aided indexing) is compared with that of a Key Word Out of Context Index (KWOC). Twenty subject searches were performed using a data base of 635 summaries of Defense management data. Results show an average recall measurement of 0.73 for machine‐aided indexing and 0.79 for the KWOC index. The average relevance measurements were 0.62 for machineaided indexing and 0.60 for the KWOC in