NEW YORK (AP) — Facebook isn't just for goofy pictures and silly chatter. Whether shoppers know it or not, their actions online help dictate what's in stores during this holiday season.

After polling customers on the social media site, Macy's decided to carry denim jeans in bright neon hues rather than pastels. Wal-Mart for the first time decided to let customers vote on which toys they want discounted. And to better plan orders for the decorative flags she sells, a small business owner in Mississippi is running a contest that encourages customers to chime in about how they're decorating their homes this winter.

The impact of social media on a company's bottom line is tough to quantify, with no hard data on how millions of Facebook fans and Twitter followers translate into sales for stores. But during the holiday shopping season, a roughly two-month period when retailers can make up to 40 percent of their annual revenue, stores are uncovering a valuable use for all the seemingly useless online muttering: market research.