You'll have to rely on indirect indicators here. (audiencebloom.com)
He predicts that information from sources such as pharmacy sales of certain medications, and even indirect indicators like the stock market, could also inform disease tracking in powerful ways. (scientificamerican.com)
Note that none of the elements of true healthfulness — your diet, fitness regimen, or management of stress — are directly tested; doctors use indirect indicators of blood pressure, weight, skin tone and color, and so on. (edutopia.org)