Now this is interesting. I remember a number of people even seeing big discrepancies with the Keyword Planner and the old Keyword Tool, in the brief time they were running concurrently.

I definitely have my doubts.

agree with this - but also think a lot of these people didn't realize that the new tool only showed 1 type of volume

I have massive doubts. I only spent about half an hour putting that study together so it's bound to be a bit flawed - it definitely looks like it's worth spending a bit more time on though!

Maybe numbers don't match, because we are trying to compare actual traffic volume with estimations based on historical data. That's the only idea which comes to my mind, but when looking at the numbers the error threshold is simply ridiculous.

The differences between the numbers are significant. It would be great, if someone from Google could explain this issue, as it concerns their main product. AdWords not only concerns search engine marketers, but primarily advertisers, so the transparency here would be essential.

As for SEO nothing changes. Keep on rolling and don't trust Google.

I replied in your blog's comment section but thought I might post the same thing here as well for others to discuss:

"Hi Luke,

I think that's the problem. You didn't include the Search Parner searches in Keyword Planner, I did it for Yamaha flute and it changed the volume from 590 to 5,400 which changed the margin of error from 670% to just 19%.

Considering 5,400 is a 12-months average and October has been the lowest month according to Google Trends, that brings the margin of error to almost 0 and the keyword planner is now accurate.

Another factor that I see might be affecting your impressions is "Exact Match Close Variant". Close Variant includes variations of the keywords such as plurals.

Let me know what you think."

High Performance Dedicated Email Marketing Servers Can Send up to 500000 Discount Offer Up to 25%..

http://instantbulkmailing.wordpress.com

Al- are you suggesting that Google's search partners supply almost 1000% more traffic than Google itself? That in itself sounds like a flaw in the tool if those settings make such a difference IMO.

Jon, yes and his Adwords analytics confirms it.

Hi Al, I think you're right to some degree - changing the Keyword Planner to include Search Partner data gets the figures closer to the PPC impressions on some keyphrases, but not for all. Looking at the [samsung ue40f6400] keyphrase, the Keyword Planner including Search Partners estimates 2,900 monthly searches - not much difference to the non-Search Partner data and still a long way off the PPC impressions of 6,902.

Luke, can you confirm please that you are advertising on "search partners" and that these partners generate 1000% more traffic than Google itself?!

Hi Jon, I just checked and all the campaigns the keywords are taken from are set to 'Search Network only'....

this information is really good... with some proofs.. Thanks for sharing

One with I noticed with GKT and prodcuts like TVS ect, they do not update the data quickly so it can be outdated on GKT. We all know that the GKT tool only gives you maybe a 25% representation of the correct data and should be treated as "guess work". I have some rankings which drive 100k UV a month and GKT shows 5k LOL. 
 

What's TVS?

TV's it is a specific product from his example "long-tail term [Samsung ue40f6400] – which is a TV.", so the data is not updated quickly on GKT. It is similar to mobile phones or any other consumer good which comes out and the data may show as been lower compared to actual market searches.

The new tool is so hopeless, I have been pulling my hair out with it recently - not helped by the fact that a local level the data is very flakey indeed. 

I've had numbers change on me mid-day. I've compared pre and post kw traffic numbers from the switch from KWT and KW Planner. The difference was great even though both were set on global, all search network, and all devices.

If there's anything you should trust more, it's your actual paid data vs Google's kw planner estimates - they are, after all, estimates.