NEW YORK -- An in-store consumer tracking initiative uses a combination of electronic eyes and human counters to document how many people travel down each aisle in stores.

The project, known as Pioneering Research for an In-Store Metric, or Prism, has been studying traffic patterns and marketing in 160 large stores since April. The In-Store Marketing Institute and Nielsen are leading the effort. Prism also measures what percentage of people who shop in an aisle actually buy something there, Advertising Age reports.

Nielsen CEO David Calhoun likened Nielsen’s In-Store to his firm’s TV and Internet ratings.

“It will allow in-store to rightfully take a seat at the marketing table and be considered in an analytical manner consistent with all good marketing and media planning,” he said. “What you can measure, you can manage.”

Senior executives from the world’s biggest advertiser, biggest retailer and biggest media-buying agency, Procter & Gamble Co., turned up at the In-Store Marketing Expo in Chicago last week to tout the new way of measuring shopper marketing.

The practice, which is growing faster than internet advertising -- doubling since 2004 and on pace for a compound annual growth rate of 21 percent through 2010, according to a draft study by Deloitte from the Grocery Manufacturers Association.

Calhoun said shopper marketing, if the definition expands to the trade-promotion dollars manufacturers pay retailers, displays or features in circulars, is already a half-trillion-dollar business.

“Shopper marketing is a new medium as important as the internet, mobile or gaming,” declared Starcom MediaVest Group North America CEO Renetta McCann at the announcement of pilot results using Nielsen In-Store’s Prism initiative, essentially a ratings system for in-store media and marketing that measures reach and frequency similar to TV.”

This brave new world means buyers need to know not just how to bet in May on ratings for fall shows but also how to hedge the price of corrugated paper for end-aisle displays.