Word of mouth (WOM) marketing is the oldest and some would argue best, form of marketing. And we all know intuitively it works. In fact, a lot of it we probably don’t even consciously notice. The average US consumer has over 100 branded conversations a week. But there is a vast gap between knowing something works, and justifying to your CEO or board why you should spend money on it.

Because there are no standard metrics, in the same way there are for TV and print advertising for example, doesn’t mean that WOM lacks of accountability. But if you’re not measuring it, you shouldn’t be doing word of mouth at all.

Measure conversations

The media metric for word of mouth is conversations. We need to know how many conversations were created as a result of something we did which gives us the reach of the campaign. The simple way to do this is to take a sample of influencers involved in the campaign and ask them to keep a diary of conversations about that product or service for a specified period of time. Ideally you would also include some soft measures around the ‘topics’ of the conversations to understand how the brand is being talked about. An incredible amount of insight can be gained from what people choose to say to others about your product.

Demand evidence

Word of mouth campaigns are designed to be passed on, and for that reason, any measurement must look beyond the first direct impact to the people it impacts at further levels — or ripples if the water analogy works for you.

Soup measures campaigns to two ripples beyond the first direct impact. Admittedly, this isn’t easy to measure, and we have had to develop a sophisticated back-end system to be able to do this; but without factoring in the conversation spread word of mouth won’t pay back. And don’t trust anyone who pulls these numbers out of the air — demand real evidence.

This spread can also be seen online. There are ways to do this through many of the social media monitoring tools but these can be lacking as they don’t include critical conversation channels such as Facebook. We often put elements in campaigns that make them more trackable online, for example adding links for people to pass on. Nevertheless, it still can be difficult to track exact online spread of a word of mouth campaign. We use both the direct ‘asking’ method of influencers and their friends combined with social media monitoring to give us a picture which is perhaps closer to reality.

Measure over time

Unlike most marketing communication, word of mouth is not one single impact. It’s something that continues to grow as the influencer — or the person we involved in the word of mouth marketing campaign — comes in contact with more people they think the information is relevant to. Any measurement must look at a time-based measure to ensure it is capturing the longevity of the campaign. I would recommend the time is dependent upon the objectives of the campaign. But, at a minimum, a dip at one month and then again three months later to track growth is a good start.

Measure the action

Word of mouth has significantly more impact beyond making an initial impression. It is the most likely media to lead to action, change opinions or influence someone to go out and buy the product someone just recommended to them. Measurement must look to include what action people took as a result of the conversation. On average, our research shows that 65% of people who were recommended a product by someone in our word of mouth campaigns will go on to buy the product. This shows the incredible power behind word of mouth as a highly targeted and relevant medium.

Using all this information you can get a robust idea of ROI for your marketing spend. You won’t need to do this all the time, but once you have tracked a couple of campaigns and you can show the evidence, management might be more likely to trust their intuition on word of mouth.