A comparison of the currency of secondary information sources in the biochemical literature. II. MEDLINE online and on CD-ROM

Abstract

The currency of selected versions of the MEDLINE database on CD-ROM and in online format was studied. The arrival of issues from 72 monthly journals and nine weekly titles during a 3-month period was monitored and their appearance in the various MEDLINE formats were recorded. Availability data for MEDLINE published by the National Library of Medicine were used as a baseline and subsequent distribution delays for the different MEDLINE formats were calculated. The study suggests a delay of approximately 2 weeks for indexing and mounting the MEDLINE file on to host computers for online access. A delay of 6-8 weeks was calculated for the MEDLINE data to be encoded on to compact disk, shipped and posted to the library customer. The currency of the MEDLINE database formats was compared with a weekly current-awareness service, CURRENT CONTENTS ON DISKETTE LIFE SCIENCES (CCOD). The majority of papers were indexed and distributed in CCOD within 10 weeks of publication date. Most papers appeared within 15 weeks in the online MEDLINE format and within 20 weeks in CD-ROM MEDLINE. The primary journal arrived at the library site within 5 weeks in most cases.