Do all those free food samples in the supermarket actually increase in-store sales? 

Yes, but that's not altogether surprising. What is suprising is just how large the increase in product sales is after giveaways. Interactions, the company that handles sampling programs at many national retailers, provided some fascinating numbers for Joe Pinsker's recent story about Costco's sampling smarts in The Atlantic. Pinsker writes: 

In the past year, Interactions' beer samples at many national retailers on average boosted sales by 71 percent, and its samples of frozen pizza increased sales by 600 percent.

For wine, the increase was by more than 300 percent. For lipstick and mascara, the increase was by more than 500 percent. (Charles Revson, the marketing legend and pricing genius who built the Revlon cosmetics empire, would be proud.)

What's more, sampling is a marketing strategy almost any type of business can benefit from--not just retailers like Costco. JadeYoga, a 12-employee maker of yoga mats based in Conshohocken, Pennsylvania, has become a beloved global brand in large part because of its generous donations policies. Moreover, it was a giveaway of mat samples--small five-by-eight rectangles of mat--that helped company president Dean Jerrehian realize yogis would pay a premium for his slip-free, eco-friendly product. In response to a mail-out of 500 samples, the company received a whopping 300 phone calls. Talk about a tipping point.

Sampling can also be a smart strategy if you set up a booth at trade shows and industry events. WordStream, a Boston-based software-as-a-service search engine marketing platform founded in 2007, lured hundreds of attendees to their booth at HubSpot's recent INBOUND conference in part because their swag was superb: A small, branded Moleskine notebook, in the bright baby blue that is WordStream's official color. "They were a little pricey, but it was worth it because people come for it and keep it," says Kate Gwozdz, WordStream's partner marketing specialist and trade show leader. 

Why does all of this matter in 2014? With the holiday shopping season creeping ever closer, retailers of all stripes remain in a struggle to lure customers out of their e-commerce comfort zones and into actual store space.

But just getting the customer into the store is no longer enough. With apps allowing consumers to compare prices in seconds, many shoppers use retail stores merely for browsing, making the purchase online. What better way than to convert visitors into customers than with a small, tasty bribe? Pinsker's piece makes a strong case that samples build customer loyalty.

"Reciprocity is a very, very strong instinct," Dan Ariely, a behavioral economist at Duke University, tells Pinsker. "If somebody does something for you, you really feel a rather surprisingly strong obligation to do something back for them."