How to measure word of mouth marketing

Here’s an article sent to me by my boss this week:

http://www.mckinseyquarterly.com/Marketing/Strategy/A_new_way_to_measure_word-of-mouth_marketing_2567?gp=1

It’s on how to measure word of mouth marketing.   The point of the article is to explain how word of mouth works because “the science behind word-of-mouth equity helps reveal how to hone and deploy that art: it shows which messages consumers are likely to pass on and the impact of those messages, allowing marketers to estimate the tangible effect word of mouth has on brand equity and sales”.

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