One of the assessed research elements in the UK's Research Excellence Framework (REF) exercise in 2014 was the research environment. The quality of the research environment was assessed by expert peer reviewers who were given a set of quantitative factors to support their decision making. However, there is no systematic procedure to integrate this quantitative information into the evaluation process. This article evaluates the relevance of quantitative factors in explaining the assessed quality of the research environment. Findings suggest submitting units with high external research income generation tend to have a better research environment evaluation in almost all the assessed subject areas. The importance given by reviewers to similar quantitative factors was distinctively different in two units of assessment (UoA) in which the evaluation criteria were the same, which highlights the internal inconsistency of the peer review evaluation. Our findings also confirm the existence of the 'halo effect' in some UoA where submitting units that belong to the Russell group and have sub-panel members in the REF exercise obtained higher scores even after controlling for the assessed quantitative factors.