How a Startup Is Helping Retailers by Using Digital Tests in Physical SpacesAn NYC startup applies A/B testing -- common in the digital space -- to convert foot traffic to sales in brick-and-mortar stores.

Y Combinator's Kat Mañalac remembers well the day last year when she met Prayas Analytics founders Pranshu Maheshwari and Yash Kothari. Mañalac was visiting the Wharton School in Philadelphia as part of YC's spring campus tour, where the accelerator scouts investment opportunities and offers winners a flat $120,000 for a 7 percent stake in their business.

"They had handmade T-shirts on," she recalls. "Yash's shirt said "I [heart] YC' and Pranshu's said "I [heart] Traction.'"