The impact factors of open access and subscription journals across fields

We have compared the 2-year and 5-year impact factors (IFs), normalized impact factors (NIFs) and rank normalized impact factors (RNIFs) of open access (OA) and subscription journals across the 22 major fields delineated in Essential Science Indicators. Journal Citation Reports (JCR) 2012 has assigned 2-year IF to 1,073 OA and 7,290 subscription journals and 5-year IF to 811 OA and 6,705 subscription journals. Overall 12.8% of journals listed in JCR are OA, but a higher percentage of journals are OA in 9 fields, including multidisciplinary (31%), agriculture (19.1%) and microbiology (19.1). Overall 2-year IF is higher than 5-year IF in about 31.5% journals in both OA and subscription journals. But among physics journals, two-thirds of OA journals and 58% of subscription journals have a higher 2-year IF. For multidisciplinary journals the mean RNIF is higher for OA journals than subscription journals. Higher proportion of subscription journals had mean RNIF above 0.5: 361 of 1,073 OA journals (33.6%) and 3,857 of 7,280 subscription journals (52.9%) had a 2-year mean RNIF above 0.5 and 277 of 811 OA journals (34.2%) and 3,453 of 6705 (51.5%) subscription journals had a 5-year mean RINF above 0.5. Moving to OA has proven to be advantageous to developing country journals; it has helped a large number of Latin American and many Indian journals improve their IF.