When you’re checking out at the supermarket this holiday season, the cashier may ask if you would like to include an extra dollar for a charity. Or, your credit card company may offer to donate a certain percentage of each purchase to a good cause. Firms often run philanthropic campaigns in hopes of increasing customer loyalty and purchases. But does it always pay off? Serguei Netessine, Wharton vice dean for global initiatives and professor of operations, information and decisions and two other researchers — Jasjit Singh from INSEAD and Nina Teng from Oxford University — examined the effectiveness of charity-linked promotions by looking at them in the context of a mobile ride-hailing taxi service. Their paper, which was published in Management Science , is titled “ Philanthropic Campaigns and Customer Behavior: Field Experiments on an Online Taxi Booking Platform .” Netessine spoke with Knowledge at Wharton about the findings. An edited transcript of the conversation follows.…