Accuracy of the data from Google Insights for search


Google Insights for Search is now two years old – Happy Birthday Insights!

I do love Google’s Insights for Search tool. Whenever I am looking at keyword opportunities for clients, the tool is there to give me long-term trends, geographical distribution and suggest other keywords I might like to have a look into.

Two years ago I ran some data from the Insights tool and compared the normalised data (the search volume is stripped and Google just give a 0-100 guide for the keyword phrases you are currently looking at) with actual impression data from one of our Google Adwords accounts.

With a little manipulation we found we could potentially use the Google Insights tool as a way of benchmarking search volumes for other keyword phrases; once you have added a couple of keyword phrases into an Insights search query you can quickly get an idea of monthly search volumes for other search phrases you wish to find out about.

Here is a chart of us testing the accuracy Insight’s data against our ‘known’ Adwords data…

Has the quality of Insights data changed?

I had happily been using this technique to look at search volume trends… Until, that is, published this post, wondering why Google had dropped so much detail from the Insights data. I thought I had better re-evaluate the data and re-run the exercise to see if Google had been tinkering with the data (and if they had by how much). People of Further, I apologise for the amount of time it has taken me to do this post: I’ve been a very busy boy.

Attempting to compare 2008 data with 2010, I pulled the latest data through my previous spreadsheet and re-mapped the figures. Here are the important bits….

1. The data you get from Google Insights today is different from what you got in 2008. See the chart below for Insights’ keyword phrase on broad match (note: I am matching the data for the same date range, hence it is only up to August 2008.)

2. When compared to 2008, the current data is under-reading by a third. When you adjust the weighting of the 2010 figures you get a fairly good fit with the 2008 data. However there are differences…

3. The 2010 Insights data appears smoothed and the peaks and troughs in the data are less pronounced.

4. The current weighting factor appears to be constant through time (i.e. it does not vary from one year to the next).

5. The same weighting factor can be applied to Insights keyword searches for both ‘broad match’ and ‘phrase match’

6. Google Adwords can still be directly compared to Google Insights data. Just how well is down to opinion – if you look at the charts below you can make you own judgment of how good the fit is and whether you think Google Insights offered clearer data in 2008 or now.

I have produced charts for (1) Google Adwords mapped onto 2008 Insights data and (2) the same data mapped onto 2010:


For your interest the chart below plots all the data at once: (1) 2008 broad match & phrase match, (2) 2010 broad match & phrase match, (3) Google Adwords data through time

What does it all mean?

My reading is that there is still real value in the Google Insights tool. With some manipulation you can still get the Insights tool to give you weekly impressions with what appears to be only a very small margin of error. I don’t believe Google Adwords gives you anywhere near this level of accuracy.

Google Insights versus Google Adwords

You will probably be thinking – “But can’t I just get accurate data from Google Adwords?”
And my return answer is “Nope, I reckon Google adjusts the search volume data in Google Adwords to stop you using it as a search volume tool.”
You go on to ask – “I don’t believe you, prove it!” or “Go on then, tell me which is more accurate, Google Adwords or Google Insights?” or “Sh!t! What am I to do? My whole Search marketing business is built on forecasts and keyword suggestions using Adwords data.”
My answer: “Search agencies with data for high volume terms will be in the best position to make their own forecasts, but the only real way to find out how accurate this process is would be to run it alongside the Adwords tool and actual volume data.”

Next Steps

It’s a quick job to compare Google Insights, Google Adwords and actual impression data so I will let you know via a blog post soon (hopefully I’ll find the time tomorrow) and I will let you know which is the more accurate.”

What are your thoughts on this? Please drop me your thoughts or questions and I will try and answer? Please leave a comment.

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