DES MOINES, Iowa (AP) — Iowa Gov. Kim Reynolds is defending her use of a tool to help guide the state’s response to the outbreak that critics have called arbitrary and unscientific. The matrix developed by the Iowa Department of Public Health looks at four data points in six regions of the state. If any one region hits 10 on a 12-point scale, the matrix calls for the potential implementation of a shelter-in-place order.

Critics include a top infectious disease researcher and other medical experts. They argue that the data points are backward-looking rather than preventive because they trigger stricter interventions only after more people are infected and hospitalized.