Sagging sales and weak response rates amid economic gloom means the time to deploy tests is now. Here are the new rules to live by. During rough economic times, it’s easy for those who control the budget to say that if response rates are down, they don’t want to invest in testing-“You can’t spend money if you’re not making money.” To certain executives, this actually makes sense. But others, the wise ones, know that the time to spend more marketing dollars is when sales are down.