being relevant: do we need to add search queries?

When analysing the search queries which have been activating your ads, it’s easy to become confused by the depth of strange search queries that Google shows your ads to. Why is the search query ‘football fixtures’ every considered relevant to the keyword ‘rugby socks’? The truth is Google doesn’t directly measure relevancy in the semantic way humans do – it’d just be too complex – how would they know that ‘Usain Bolt’ isn’t related to ‘nuts and bolts’, and that ‘Cheryl Cole’ once was, but is no longer, relevant to ‘Simon Cowell’?