Copyright (c) 2020. This is an Accepted Manuscript version of the following article, accepted for publication in Human Factors and Ergonomics in Manufacturing & Service Industries. Paul M. Salmon, Gemma J. M. Read, Guy H. Walker, Nicholas J. Stevens, Adam Hulme, Scott McLean, Neville A. Stanton. (2020) Methodological issues in systems Human Factors and Ergonomics: Perspectives on the research–practice gap, reliability and validity, and prediction. Human Factors and Ergonomics in Manufacturing & Service Industries 3. It is deposited under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited.