Facebook's long-awaited IPO launched on Friday, valuing the company at a whopping $100 billion. And just as the investor community sent a somewhat mixed message in the first day of trading, the marketing community, too, is starting to ask questions.

Questioning the effectiveness of the practice, GM has decided to stop advertising on Facebook, according to several news reports. The news comes on the heels of comments by WPP Chief Executive Martin Sorrell that "clients, for the very first time, are starting to question the measurement issue" on social media.

"The area is a very sexy area, and clients have gone in almost willy-nilly, because it's fashionable to do so," Mr. Sorrell told The Wall Street Journal, adding that finance departments "are increasingly starting to look at the value of those investments."

We believe that the discussion about social media's effectiveness is both timely and appropriate. What Facebook has accomplished is hugely impressive. But while Facebook has proved the power of "social," it has not yet proved the power of "social media" to generate growth for brands and businesses. When taken in the context of the "total social" opportunity, online social marketing is one very small part of the picture.

In fact, our firm's research finds that less than 10% of word-of -mouth about brands occurs online, while more than 90% happens in the real world. We also know from our research that these real-world conversations -- most of which are face-to-face -- bring with them more credibility, enhanced desire to share with others and a greater likelihood of purchase, compared with online conversations.

If brands want to be social and generate conversation -- and we strongly believe they should -- they must tap into the far bigger and more powerful force of real-world, face-to-face conversation. They have many available pathways.

It is important to fight the urge to start with a particular tool or channel. We agree with Facebook Global Brand Experience Manager Paul Adams who says, "You need to reorient your business around people, not technology. Don't have a Facebook strategy, or a Twitter strategy or Foursquare strategy. Map to human behavior and not to technology."

Instead, begin by asking "What's my brand's story?" What are the messages about your brand and category that make you talk-worthy? Emotions are what propel people to talk and share, and you need to determine the emotional connection between the consumer and your brand or product.

Next, it's important to know who is already talking about your brand or can be encouraged to do so. Who are the consumer influencers and brand avocates in your category? When and where do they talk, about what and why?

Only when you have an understanding of the stories and the people who will tell them does it make sense to focus on the best channels for reaching others. It turns out that the biggest, most productive channel for sparking conversation is not online social media but paid advertising. People might say they no longer trust advertising, but it definitely gets them talking. And the closer they get to purchase decisions, the more they talk about ads. An effective advertising strategy is to reach people who already love your brand and give them new reasons to sell it to their family, friends and co-workers.

Owned media like a brand's website, or promotions such as coupons, can be effective. And, yes, sometimes social media is the channel through which to distribute such content. When it fits the strategy, embrace it. But don't start there as a matter of reflex.

Today's consumer marketplace is highly social, but not because of particular platforms or technologies.

The businesses that will be most successful will embrace a model that puts people -- not technology -- at the center of products, campaigns and market strategies.

The great social wave is an opportunity that no business can afford to ignore. It's happening, and to the continuing surprise of many, it's mostly happening face-to-face, involving all forms of media and marketing. Ed Keller and Brad Fay are co-authors of "The Face-to-Face Book: Why Real Relationships Rule in a Digital Marketplace." They are also principals of the Keller Fay Group.