The findings are the latest example of how the notion of a single price is breaking down in the digital age, a trend economists say could be pushing up some prices.
In tests in four cities across the country, nearly 200 volunteers checked prices on 20 grocery items on Instacart. They found differences in item after item.
A “Mistress Dispeller” is an expert at infidelity: part marriage counselor, part private eye. The filmmaker Elizabeth Lo followed one mistress dispeller for three years, and it had a surprising effect on her own love life.