Let's pretend, for example, that we could find a scientifically valid study that shows that people spend 25 % more when using a credit card than they do when spending cash. (money.stackexchange.com)
For example, there are no statistically valid studies comparing the response of a mixed - learning - style control group with the results of a learning - style - matched group. (edutopia.org)
But the point is, we should just test things — with valid study designs. (culturalcognition.net)