Supplement to Push-Me Pull-You: Comparative Advertising in the OTC Analgesics Industry. For Online Publication

4. We assign a number of milligrams to each product, according to the strength of its primary active ingredient. To do so, we combine the descriptive data in the Nielsen dataset with the data of milligrams of a speci…c active ingredient in a speci…c formula. In the case of Ibuprofenand Naproxen Sodiumbased pain relievers, the assignment was straightforward, since these OTC products can come only in 200mg (for Ibuprofen) and 220mg (for Naproxen Sodium). In the case of Aspirin and Acetaminophen, the situation is more delicate, since these products can come in varying strengths and as a combination with other analgesic agents. Therefore, we consider whether the product is of regular strength, extra strength, body and back pain (which includes ca¤eine), and rapid headache; whether the product is for rapid release; whether the product is for children; whether the product has a sleepaid; whether it is for arthritis; for migraine, for menstrual purposes; or for sinus headache.