 Model-based accounts have been developed by studying measurement practices in the sciences, and particularly in metrology. Metrology, officially defined as the “science of measurement and its application” (JCGM 2012: 2.2), is a field of study concerned with the design, maintenance and improvement of measuring instruments in the natural sciences and engineering. Metrologists typically work at standardization bureaus or at specialized laboratories that are responsible for the calibration of measurement equipment, the comparison of standards and the evaluation of measurement uncertainties, among other tasks. It is only recently that philosophers have begun to engage with the rich conceptual issues underlying metrological practice, and particularly with the inferences involved in evaluating and improving the accuracy of measurement standards (Chang 2004; Boumans 2005a: Chap. 5, 2005b, 2007a; Frigerio et al. 2010; Teller 2013, 2018; Riordan 2015; Schlaudt and Huber 2015; Tal 2016a, 2018; Mitchell et al. 2017; Mößner and Nordmann 2017; de Courtenay et al. 2019).