We are now used to seeing maps of the rates of infection across Ireland. The data used for this map is the daily county-level testing information that is made available by the Dept. of Health. Since these data were first reported on March 16th there have been 59 updates. Over the same period the testing procedure itself has changed considerably as we shifted from a process that tested everyone identified as potentially infected to testing those that have two symptoms and are in high risk communities. In addition, for a period there was a significant lag in processing samples (>2 weeks), resulting in a sudden increase in positive cases when the accumulated results became available. The current testing regime could be described as purposeful sampling in that it is focused on specific communities and jobs. These reports, even if they do not inform us about the rate of infection in the entire population, show us the evidence that is guiding policy.