AdWords Dynamic Keyword Insertion (DKI)

Published on July 9th, 2007 by Jeremy Chatfield

Click Through Rate, abbreviated as CTR, is a crucial factor in AdWords advertising. Improve the CTR and you can perversely reduce the cost per click. With a high enough CTR, you can achieve the high prize on AdWords, of position 1 at a $0.01 per click. You can’t achieve this for every keyword, however, or even most keywords.

One technique is to repeat back the key parts of what the other party has just said. This “mirroring”, as it is sometimes known in marketing communications, helps to tell the other party that you have heard their message and your answer is relevant. In the case of AdWords, this would mean making sure that the advert echoes the search string. You can’t do that precisely, except when the keyword exactly matches the search string. The best that you can do is to dynamically insert the keyword that Google has matched.

You can see the effect of this text replacement in some adverts. You’ve probably seen examples of adverts that say strange things like “Killer Bees/Feed your passion” or “Skyscrapers/feed your passion”? You can see that these adverts have a common format, except for the keyword.

A minor diversion at this point to cover terminology. When a user types something at a search engine, that’s usually known as a search, or search query. What you, as an advertiser, gives to Google (or to MS Live, or Yahoo!Search Marketing), is a “keyword”, which is a single word or a phrase that you hope will be a close match for something that users will search for.

If you use “Exact Match”, then the search query must be exactly the same as the keyword, with the exceptions that punctuation is removed (no “.”, no “:”, no “,”) and all letters are treated as if they were lower case. So “gandalf the white” as an exact match will match “Gandalf The White”, but will not match “gandalf the white or grey”, and “links merjis com” as an exact match will match the search “links:merjis.com”.

If you use Phrase Match, then all the words that are in the keywords must be present in the search query, in the same order. The phrase match “gandalf white” will match “gandalf the white wizard”, but not “white wizard gandalf”. Note that Google learns how to extend phrase match. You may find that when you start, it doesn’t even show the advert for the exact text in the phrase match. Only with experience does it learn to allow suffix, prefix and infix words.

When you get to Broad Match, then the matching can be a lot looser. When you use Google’s Broad Match (the default) or enable Yahoo’s Advanced Match, then you give the Search Engine a licence to get wild with the matches. Here’s a few examples – these are made up, rather than revealing customer information, but the patterns are the same as examples of broad match that we’ve tracked:

• “new york ticket price” could be matched to searches for “train ticket price” or “princes concert ticket london”
• “family vacation” could be matched to searches for “cheap flights”

Problems?

Dynamic keyword insertion sounds like a great tool. Raising CTR, and allowing you to have larger AdGroups, with advert text that responds to user search. Surely there aren’t any problems?

Well, what if your keyword is something like “Washington State University”. That’s more than 25 characters, so you can’t use that in the headline. If the keyword was “Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch”, you’ll break the 35 character limit for a description line.

Fortunately, there’s a way to overcome this problem. If the keyword is too long, then a user supplied default text is used. If the keyword is that long Welsh place name, then you could use “{keyword:Llanfair PG}” and the long string will be replaced in the advert by “Llanfair PG”.

If the keyword is too broad, such as a single word, then you might find that the advert loses the impact. For example, if advertising a Jeep Grand Cherokee, you used the keyword “Jeep”, and had added a bunch of negative keywords to make this advert only likely to show for a Grand Cherokee, then DKI will put just “Jeep” into the advert. While you may have reached the audience that you want, the impact of the message is diluted as DKI can’t compensate for the negative keyword usage. In other words, if the CTR will be raised by not using DKI, then consider breaking the AdGroup into new AdGroups where DKI will help and other new AdGroups, where DKI probably won’t work well.

DKI Usage

Using Dynamic Keyword Insertion is really easy. Add “{keyword:default text here}”, and replace “default text here” by whatever it is that you want shown if you have any overlength keywords. You can insert the “{keyword:…}” anywhere in the headline, or anywhere in the two description lines, with no problems, except that you may end up with unintended semantic nonsense like incitements to trade skyscrapers and killer bees.

There’s a couple of subtleties to DKI. English language users usually respond better to adverts with initial capital letters in the copy. If you use “{KeyWord:…}”, then when the keyword is inserted, each first letter is capitalised. And if you use “{Keyword:…}” then only the first word of the keyword is capitalised. Examples, based on a keyword of “zang tuum tumb“:

• “{keyword:propaganda}” -> “zang tuum tumb”
• “{Keyword:propaganda}” -> “Zang tuum tumb”
• “{KeyWord:propaganda}” -> “Zang Tuum Tumb”
• “{KEYWord:propaganda}” -> “ZANG Tuum Tumb”
• “{KEYWORD:propaganda}” -> “ZANG TUUM TUMB”

Destination URL? Really?

You can even use DKI in the Destination URL, though when you do that, you don’t need the replacement text string. This allows you to pass the keyword to a web server, and to web analytics packages. Most web analytics packages make a pigs ear (or a dogs breakfast) of handling paid search, so this may be less useful than it seems. Even worse, you can’t pass in the match type automatically… So you have no idea when you see a keyword, what it was supposed to be doing.

In a Destination URL, “{keyword}” is replaced by the text string of the keyword, with spaces suitably replaced (e.g. turned into “+”).

Content Match

If you use content match, there isn’t a keyword. There’s a gestalt of meanings, but no specific keyword. What does Google do in this case? There’s no Google documentation about this – or if there is, it is new!

Experiments suggest that Google uses the substitute text. Make sure that the text makes sense when there is no actual search.

Summary of DKI

Use DKI in the headline, or the two description lines, to improve CTR, especially in AdGroups with large keyword lists.

Watch out for peculiar implications – imagine what each and every keyword will look like in the context of the advert, and lose the wierder and more disturbing messages that you can get, by putting those keywords into a different AdGroup.

Use DKI in the Destination URL to help web analytics to interpret paid search activity.

Don’t use DKI where usage would reduce CTR.

Update

03-Mar-2008 : Google now has their own, pretty comprehensive tutorial on using DKI in AdWords.