Online comparison shopping has left you overwhelmed by options and contradictory reviews, and all you need is a little in-person guidance to choose the right product for your needs. At the store, you find a sales floor so deserted, you almost expect to see tumbleweeds rolling by. When you finally do get help, it’s from a poorly trained sales associate who knows even less than you do. You leave the store unsatisfied and possibly empty-handed.

Then again, maybe you’ve experienced the opposite: an experienced, knowledgeable salesperson who knows how to help you find the perfect item. Retailers and customers alike have long reported that expert sales associates offering advice lead to happier shoppers and, in turn, more sales. Now, those reports have been validated in data that shows exactly how such knowledge can impact a customer’s sales experience – and a retailer’s bottom line.

High-quality help makes the biggest difference in getting a prospective customer over the hump from “just looking” to happily buying, according to the Retail Experience Survey involving more than 600 U.S. consumers. In fact, the data showed that nearly three-quarters of consumers walk into a store looking for advice from a product expert.

And just how much is a knowledgeable, helpful sales associate worth to a retail business? Researchers at the University of Pennsylvania Wharton School recently set out to answer this question. The study, The Value of Helpful Expertise in Retail, followed more than 63,000 sales associates at 330 retail locations over two years to find out how salespeople who completed product training affected sales.

Sales associates received customized product training from Experticity, a network that helps them build their brand expertise and get rewarded for their knowledge by the brands themselves. The results of study were staggering. Sales associates who completed a single training course sold 69 percent more than those who didn’t. And those who completed just six training courses sold a full 123 percent more.

“Retailers that want to boost their sales and build loyal customer advocates must invest in great buying experiences by offering customers knowledgeable help, and right when they need it,” says Experticity CEO Tom Stockham, “The role of store staff has changed from simply serving customers to informing and guiding their choices.”

These days, as brick-and-mortar stores struggle to redefine themselves in the face of online competition, putting a human face on helpful expertise is a smart way to stand out from the crowd and get customers in the door. That means making sure sales associates have the information they need to give customers expert advice right when they’re deciding what to buy.

“This study data provides evidence of what we’ve all experienced in our own lives as consumers,” Stockham says. “The way forward for retailers involves focusing on providing excellent, knowledgeable customer service that results in better, more productive experiences for customers.”