How can we understand the uncertainties in high-stake measures such as PISA in relation to the claims that different authorities make from them? In this paper, we use a rather remarkable case from Sweden involving conflicting interpretations of the PISA 2018 results at a national political level and afight over statistics between two national agencies: National Agency for Education and the National Audit Office. The aim of this paper is to unpack processes of interpretations and claims that are often black-boxed in PISA debates: How can we understand the process that led up to the fight and what followed? Our data consist of media articles, broadcasts from the national television and radio (2018–2021), reports and memos from the two-state authorities involved in this debate, and email conversations between the two. Our results stress the need for further transparency in how PISA data are collected and calculated.