Alan Mitchell of Calculate Marketing wrote over a year ago that many may be paying too much for their Google Adwords clicks. In an article on Search Engine People he gave this example:

To see why, let’s suppose you have four Google AdWords keywords:

• red bikes
• red bikes sydney
• men’s red bikes
• men’s red bikes sydney

All four of your keywords are set to phrase match, meaning that they can only be triggered on Google if the searcher types a search query which includes that keyword as a phrase (i.e. those words in that order, plus anything before or after the phrase).

Each of your 4 keywords are in their own ads groups, and have their own tailored ad messages. The ad messages for your keyword ‘men’s red bikes’, for example, mention ‘Men’s Red Bikes’, and takes visitors to a page on your website showing your range of men’s red bikes.

Now suppose someone searches Google for ‘men’s red bikes sydney’. Which of your 4 keywords will be triggered?

The answer is any of them.

Even though your keyword ‘men’s red bikes sydney’ very closely matches the search ‘men’s red bikes sydney’, your more generic keyword ‘red bikes’ could also be triggered, as this also satisfies the criteria of phrase matching. You could therefore be showing your more generic and less relevant ‘red bikes’ ad message, and taking visitors to a generic red bikes page on your website, even you have a much better ad message tailored to ‘men’s red bikes Sydney’, which instead takes visitors to a page on your website showing your men’s red bikes in Sydney.

Google’s Help Centre points out that when multiple different keywords are eligible to show for a certain search query, Google will choose to show the keyword which has the highest Ad Rank. Ad Rank is made up based on a combination of Quality Score and CPC bid, meaning that all other things equal, if you have a higher bid for one particular keyword, that keyword will have a higher Ad Rank and therefore be more likely to show:

“When several ad groups contain keywords that match a search term, the system will prefer to use the keyword with the highest combined Quality Score and cost-per-click (CPC) bid. We call this combination Ad Rank.”

What this means is that with a higher CPC bid, your more generic keywords which have a relatively low CTR and Quality Score, are more likely to show compared to your keywords which are more targeted and have a high CTR and Quality Score.

Mitchell illustrated an example which  makes the Search Engine People article very much worth reading.

Mitchell approached this topic again today after reading an article on 3Q Digital. The article, “Help, Google’s Showing the Wrong Ad!” Katie Walton explains that this is known as Search Query Crossover.

Ms. Walton explains some steps you can do to overcome this, from the article:

What Can You Do to Prevent Crossover?

There are a few ways around this problem:

1. Only use exact match on head terms. Personally I don’t like this option – especially for a new campaign – you’re preventing all kinds of weird and wonderful search queries that just might be profitable that your keyword research may not have discovered.

That said, it is a sure-fire way to ensure that your head term isn’t gobbling up the impressions. (Assuming you’ve opted out of near match, of course.)

Note: A variation on this concept is the 3Q Digital way – using an Alpha Beta Account Structure to both capture new queries and have complete control over converting keywords. Download their guide for more on this approach.

2. You might choose to bid lower on your short tail keywords and higher on more specific longer phrases. You should be willing to bid higher on the phrases that are more likely to convert, so this is a logical approach to structuring your bids.

However, bid is just one aspect of the ad rank calculation, so this alone is rarely enough to prevent crossover.

3. Use negative keywords to reinforce your structure and ensure that the right search queries match the right ad groups.