How many keywords should you place in one ad-group?
It’s an age-old question for paid search marketers.Traditionally ad-groups have been considered organizing baskets for keywords. All the variations on a particular keyword, and/or all the keywords driving to a particular product or product category, are often placed into a single ad-group.
It’s common to see campaign and ad-group structures which mirror product categories and sub-categories, for example.
When the question of ‘how many’ comes up, the answer is often given as a number. I’ve never understood this. Why does the number of keywords matter?
Even the Yahoo Smart Start Guide (PDF) suggests “While there isn’t a magic number of keywords to include, you may want to start with no more than 20 – paired with two or more ads – and adjust from there.”
Consider The Text-Ads
Here’s another way to think about it. What you’re really organizing with ad-groups is text-ads, not keywords.
Each text-ad in an ad-group should be a different attempt to answer the same questions, or attract people with the same interests. It doesn’t matter how many keywords you place in an ad-group as long as the queries each of them is likely to be matched with are all appropriately served by those ads.
You’re playing Carnac, writing answers to questions that are going to come along later. The keywords you put in that ad-group are your only chance to ensure that your answers are going to be relevant to their questions.
If there are 20 keywords then there are 20. If there are 100 then there are 100.
When To Split Ad-Groups
Leaving the numbers aside, there are two smart reasons to subdivide the keywords in an ad-group. Both are based on the idea of matching your text-ads more closely to the search queries and keywords.
One is to separate keywords by subject terminology – a focus primarily on nouns – so that the specific keywords are repeated in your text-ads and on your landing pages. This is done primarily in service to the gods (or slave drivers) of quality-score.
The other is to separate keywords by qualifiers – verbs, adjectives, or other modifiers. This is done primarily to better align your text-ads with the expressed or implied intent of the users. In most cases it also brings along the quality score benefit too.
Would you want to present the same text-ad to someone looking to ‘buy a house’ as someone trying to ‘sell a house’? How about someone wanting ‘bell bottom jeans’ vs one looking for ‘stone washed jeans’. ‘discount headphones’ vs ‘3-driver stereo headphones’?
The more narrowly you can segment your user queries, which you control via keywords and match types, the better your click through and conversion rates will be.
Divide and Conquer
The topic of organizing campaigns is one I hope to cover extensively in the coming weeks. This post was inspired by one over at PPC Hero talking about the benefits of breaking down ad-groups.