The document discusses using Facebook ads to recruit participants for market research studies. Specifically, it explores targeting ads to audiences based on inferred characteristics and behaviors rather than just stated interests. This approach aims to find potential participants that match the actual screening criteria for a study, which often cannot be openly stated. The document also covers risks to consider, such as ads being shared more widely than intended or participants attempting to deceive researchers. Qualitative screening briefs are provided as an example, showing what criteria must be used versus what can be publicly stated.