WOM imagePositive WOM is often cited as the ultimate customer/business goal. Net Promoter Score® is used by many companies to measure the relative weight of positive and negative WOM uttered by customers, and a growing number are investing in word-of-mouth marketing campaigns, instead of media advertising. You’d be forgiven for thinking that WOM is seen as the ultimate free lunch. Satisfy your customers – or pay WOMM campaign participants to buzz your brand – and watch them influence others on your behalf. Some commentators call it ‘free advertising’ though strictly speaking it isn’t advertising at all, because it isn’t paid exposure in media. It’s interpersonal influence.

Let’s just pause for a moment and think about what happens. Simple mathematics tells me that if I tell 10 people about my amazing customer experience at Joe’s Gourmet Diner, and each of those 10 tells a further 5, my good news story has reached 50 people. And wow, if each of those 50 tells a further 3 people then my WOM influence has reached 150 people. If that sounds too good to be true, that’s because it is. Too good to be true. I mean. WOM doesn’t work that way. Why?

Let’s review the message pass-on process. I tell my story to 10 people in my social network. Those 10 people are what WOM experts call Generation One, or Gen1. Each of these 10 passes on the good news story to 5 Gen2. Can you assume that these Gen2 people are all new recipients of the message? No, you can’t. That’s because of the transitivity of relationships in social networks. All social networks possess some degree of transitivity. A fully transitive social network is one in which every member knows every other member. Transitivity means that it is likely that at least some of the 10 people who are all members of my social network are already connected to each other, as well as to me. Friends of mine are likely to be friends with each other. And they talk to each other. Transitivity means that you cannot assume the the WOM message reaches 150 people over 3 generations. Some people will receive the message more than once, because of transitivity. Indeed, it is entirely possible that a Gen1 talks to someone that I already spoke to as one of the original 10 message recipients, or maybe two Gen1 talk to the same Gen2. This means that the maximum possible reach of the message is 150 – only if every new person receiving the message is unique; the actual reach may be much, much lower, because of transitivity.


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