"Even if there's a national order, we have to follow what the state is doing," says
Ali Mokdad, a professor of health metrics sciences at IHME. "People will follow the rules of their own state."
... state action is what matters
IHME's model forecasts the outcome for each state by taking into account not just which measures state officials have imposed, but also the date on which officials imposed the measures and how much transmission was already underway by that point, as measured by the number of COVID-19 deaths. The model also considers how strict the measures are, with the greatest weight given to states that have imposed all three of the following options: closing educational facilities, closing nonessential businesses and issuing stay-at-home orders. The model is then adjusted based on what portion of a state's residents those various rules have been applied to. For instance, are the measures limited to certain cities or counties? Or are they statewide rules?