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Quality Score - Unscrambled

by mattobrien on March 10, 2011

So, how do you measure quality score?

We all know that quality score is important. There are several benefits of achieving a high quality score, possibly the most important of being able to achieve a higher ad rank and a lower cost per click, no-one wants to over-pay for a click. But just how do you measure your campaigns quality score?

As each keyword is assigned it’s own individual quality score between 1 and 10, the simplest way to calculate the overall quality score for your paid search campaign would be to add up all quality score for each keyword and then divide by the number of keywords. Sounds straight forwards, so how does this look in practice?

Example 1 – Keyword Quality Score

Keyword Quality Score
KW 1 10
KW 2 7
KW 3 7
KW 4 7
KW 5 7
KW 6 6
KW 7 6
KW 8 5
KW 9 4
KW 10 3
Total 62

If we add the quality score of the 10 keywords together we get a total of 62. Dividing 62 by the number of keywords (10) gives us a campaign quality score of 6.2.

However this only shows us the average quality score of the keywords within the campaign. The drawn back of looking at quality score in this way is that it doesn’t account for the different volume of impressions and clicks that individual keywords deliver. In example 1 the campaign quality score is 6.2, however if only one keyword delivered impressions then the quality score would in practice be that of the single keyword, potentially higher or lower than 6.2. So looking at an average quality score of the keywords within the account only tells you the quality of the words in your account, not the quality of words that are delivering traffic in your campaign.

If we want to know the campaign quality score based on the keyword that deliver traffic to the campaign, were also need to look at the volume of traffic they deliver to give a ‘correctly’ weighted campaign quality score.

Example 2 – Impression Quality Score

Keyword Quality Score Impressions Impression Quality Score
KW 1 10 500 5,000
KW 2 7 1,000 7,000
KW 3 7 1,000 7,000
KW 4 7 500 3,500
KW 5 7 500 3,500
KW 6 6 5,000 30,000
KW 7 6 4,000 24,000
KW 8 5 5,000 25,000
KW 9 4 3,000 12,000
KW 10 3 4,000 12,000
Total 62 24,500 129,000

To calculate the quality score weighted by the impressions delivered, we need to multiple the impressions by the quality score of the keyword that triggered them, 500 impressions at a quality score of 10, give a total of 5,000. The total for the campaign comes to 129,000. We then divide this by the total impressions (24,500) to give an impression weighted quality score for the campaign; in this case the impression quality score is 5.3. This is a significant drop in the campaign quality score in comparison to purely looking at the keyword quality score. The campaign quality score falls due to more impressions being delivered against words with low quality scores, rather than those with a higher quality score.

Keywords 6 to 10 account for more than 85% of the campaign impressions, but also have a quality score below 7, lowering the overall average down significantly. Knowing this means that efforts can be focused on these specific keywords, with the ability to prioritise by the volume of delivered impressions, thus making the biggest improvements to this measure of campaign quality score.

We would argue that this is the more pure way of measuring quality score as it is reflective of the number of times your ads are shown and the opportunities you have to convert searchers into customers.

There are other ways to look at campaign quality score, including by clicks and spend, so the next time you are having a conversation about quality score make sure you look it in more than one way and most importantly use the information to act to improve the quality score in your campaign, after all the higher the quality score, the

Unscrambled produced great results in a relatively short space of time
and at great

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