Why are some health-related products missing?
In selecting product categories, we were limited by the kinds of advertisements available in the J. Walter Thompson Company’s Competitive Ads Collection. (See FAQ 3.) In that collection, some types of products seemed to be missing or poorly represented; for example, we found relatively few pain relievers prior to 1955. We do not know why these gaps in the collection exist. It may be that the JWT Company did not have a client who wanted to market a pain reliever, or that some old files of advertisements were lost before the collection came to Duke.
