Author's accepted version (postprint).This is a post-peer-review, pre-copyedit version of an article published in Maritime Economics & Logistics (2012). The definitive publisher-authenticated version Mathisen, T. A. & Jørgensen, F. (2012). Panel data analysis of operating costs in the Norwegian car ferry industry. Maritime Economics & Logistics, 14(2), 249-263. doi: 10.1057/mel.2012.2 is available online at: https://doi.org/10.1057/mel.2012.2