Share of Voice for Search

A brand’s Share of Voice (SOV) for Organic Search is the proportion of search traffic to the brand’s website. It is defined in the context of a topic, i.e., a set of keywords and phrases, and in the context of a set of competitors, i.e., the players in the target market. And it is measured in terms of click through rates (CTR), which depends on the position of the site’s pages on SERP, versus that of competitors.

Competitive Set

To compute SOV, the first step is to identify the competitive set, i.e., the players in the target market, the competing brands. For example, the competing set for business schools in Singapore will be — NUS Business School, Nanyang Business School, Singapore Management University, INSEAD, etc.

Topic

The next step is to define the topic in terms of a set of keywords. For example, the topic might be Executive MBA comprising the keywords — Executive MBA, EMBA, Executive MBA programs, best Executive MBA programs, top Executive MBA programs, Executive MBA rankings etc.

Computation

Then, for each keyword, determine the search traffic volume and the rank of each brand on search engine results page (SERP).

CTR estimates can be derived from the brand’s rank in SERP. So, for instance, if NUS Business School ranks first on the keyword “Executive MBA programs”, the school’s estimated CTR, obtained from Exhibit 27.7, is 30% for the keyword.

The Search SOV of a brand (b₀) is its share of clicks weighted across all keywords for the topic:

$$Search \,SOV (b_0)={\sum^{all \,keywords} Keyword \, \,Weight×Share \,of \,Clicks}$$ $$Search \,SOV (b_0)={\sum_k^{all \,keywords} \frac{Volume_k}{\sum_j^{all \,keywords}Volume_j}\\×\frac{CTR_{b_0\,k}}{\sum_b^{all \,brands}CTR_{b\,k}}}$$

Note: The high click-through rates in the upper ranks of search results reflect also the ability of search algorithms to accurately extract the pages that their users are seeking.