evidence: Raising Taxes Leads to Higher Prices, but Lowering Them Leads to Greater ProfitsNecessities such as food and medicine are largely exempt from sales tax in the United States. But until recently, this dispensation had not been extended to tampons and sanitary napkins. Menstrual hygiene products have historically carried an additional cost burden—the so-called tampon tax, which its opponents say systematically and unfairly penalizes women. Advocates worldwide have argued that sanitary products are also necessities and shouldn’t be taxed. In response, 13 US states have removed the tax on tampons and sanitary pads. But this action isn’t an efficient way to help women, particularly lower-income women, suggests research by University of Texas PhD student Ziyue Xu. To study the issue, Xu analyzed scanner data collected by point-of-sale systems from the Nielsen Datasets held at Chicago Booth’s Kilts Center for Marketing, which cover a wide range of products, categories, retail channels, stores, and geographic markets in the US. Focusing on figures from the four largest nationwide retailers, she compared data from Illinois, which rescinded a 6.25 percent levy on menstrual products in 2016, with numbers coming from other states that continued levying the tax.