How Accurate are the Keyword Tool Monthly Search Figures?

Posted in Articles By Sam Applegate

keyword research - google adwords - estimating traffic


Let's define a couple of things here. Traffic is the number of visitors your website receives. Search volume is the number of people which search for a given keyword.

They are two very different things. The Adwords Keyword Tool has no idea on your potential traffic. It can however, be very useful for determining search volumes for keywords (which can then be used to start estimating potential keyword traffic).

When people grumble that the figures are wrong, it's usually because they're not looking at the correct data, or are making incorrect assumptions.

Just How Accurate is the Google Adwords Keyword Tool?

Let me prove to any doubters out there, just how accurate this tool is at ascertaining search impressions for any given keyword.

My plan is to use some actual data I collected whilst bidding, and compare it to the Adwords Keyword Tool monthly search volume estimations.

I'm using a 16 day period from 16th May to 31st May last year, so first have to filter all data accordingly.

filter adwords campaign by date

Next I enter my ad group and take note of how many impressions the exact match keyword of [web design bath] received in this period.

keyword impressions example

Now lets compare that to what the Google Adwords Keyword Tool thinks our volume should be. I type in my keyword and select exact match from within the tool.

google adwords keyword tool example usage

We see that 880 doesn't match my actual number 395. But I only bidded for 16 days, so need to extrapolate the actual impressions for the whole month.

(395/16) x 31 = 765

We're getting closer, but still need to do a few more steps. Lets make sure the Keyword Tool is only returning local (UK) search volume, as this is what I was bidding on. So, select columns, and then local monthly searches.

google adwords keyword tool example usage

Closer still. But we're still not looking at the correct data. Local monthly searches is defined as the approximate 12-month average number of search terms matching this keyword. Many keyword search volumes are seasonal, so we need to fetch May 2011 data and compare it with our actual impressions. Select columns and then local search trends.

google adwords keyword tool search trends

Then download the data into excel to see the exact numbers.

download data from adwords keyword tool

You should get something like this.

excel spreadsheet showing trending search volume

We see that May was actually a good month for this keyword. It received an above average volume of searches. So 880 has moved us further away from our extrapolated actual value of 765. But fear not, there is still more to dig out.

If we head back to our adwords campaign for this keyword, we need to look at a couple of things. First make sure you are only looking at searches from Google itself, ignoring search partners and content network impressions. To view this you need to select segment from the ad groups area, and choose: network (with search partners).

view segment data search network

Also, add the impression share column.

impression share column in adwords

Then scroll down to the ad group which holds our keyword.

adwords ad group example

First of all, we can see that the data is not being diluted with search partner or display network impressions (one of the reasons I chose this example). By looking at the impression share column, we can also see that the ad group only captured 87.53% of the total search queries which it was eligible for. This is usually due to the keyword falling off the bottom of the first page from being out-bidded by competitors.

So lets normalise our value to 100%:

765/87.53 x 100 = 874.3

Boom! That's pretty close to the 880 searches which the Adwords Keyword Tool estimated for that month.

But a couple of reasons why this number still isn't 100% perfect:

1. Because I only collected data for 16 days, I had to extrapolate the impressions to get a monthly figure. This may cause some inaccuracies as keyword search volumes may have trends within the month itself, i.e. more searches at the beginning of the month, and less towards the end.

2. The 87.53% impression share relates to the whole ad group and not just my [web design bath] keyword. As the ad group contained other keywords, I've assumed each keyword lost an identical % of impressions (there is no way to fetch individual keyword impression shares from inside the ad group). This is of relatively small significance, however, as [web design bath] was by far the most popular keyword in this ad group (accounting for around 75% of all impressions).

3. Finally, I suspect the 880 figure given by the Keyword Tool is rounded to 2 significant figures.

Remember that search volume does not equal traffic! Those 880 searchers are not all going to arrive on your page. Estimating traffic is another kettle of fish.

So there you go! Try it yourself, the Google Adwords Keyword Tool seems to use actual historical data and is therefore spot on for estimating search volumes for given keywords.

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Sam Applegate

About the Author

is a UK based SEO consultant. He is also a keen blogger, poker player, world traveller and fitness enthusiast. Read more on his about page.

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