If you want to increase your business in the new year, a simple "thank you" goes a long way with customers, according to a recent study.

The study focused on an upscale restaurant. When comments made by satisfied customers were acknowledged by the company president, repeat business increased by 50 percent, according to PsyPost. A gesture of thanks was just as effective as rewards that would cost the company money, like gift cards.

"Sweetening the pot with rewards really didn't matter," Clay Voorhees, Michigan State University associate professor of marketing and lead author of the study, told PsyPost. "These findings suggest that simple, sincere gestures are enough to drive feelings of gratitude among consumers."

"In the restaurant industry, where 5 percent is a big deal, 50 percent blew our minds," Voorhees said.

The increase in party size grew too.

"So it wasn't just that they came back," Voorhees told PsyPost, "but that they came back and brought more people with them."

Party size among women was astonishing to researchers, with a 79 percent increase.

But beware the automated response.

"Delaying the acknowledgement is critical to ensure it comes across as being more personal and sincere," Voorhees told PsyPost.