Strange SERP behaviour

[Special]

We were ranking 2nd while Google was showing only natural listings. Earlier this year, the same SERP started showing only three natural listings, followed by some business listings. We were included within the business listings, but were 3rd, so 6th overall. After a few tweaks we managed to become the 1st business listing, so 4th overall.

Early last week, the SERP changed again. The business listings were removed and replaced with natural listings. Rather than return to the old rankings, though, the order of the sites was exactly the same as it was with the business listings being there. It felt almost like a bug. So we remained 4th.

On Friday, the business listings returned! But the rankings are way different. The three natural listings at the top are the same as before. Then there are 7 business listings, and then more natural listings after that. We are the fifth natural listing of the second group, so have been hit rather badly.

Can anyone shed any light on what's going on here? We made a major change to our site 10 days ago, but it seems there's too much going on for it to be that.

If it helps, the search term is a two word name for what we do, followed by the name of our city - and we're in the UK. Coincidentally, someone from Google called earlier this week to confirm an address change I'd be trying to correct in Google Places.

[danrawk]

hi

it could be a lot of things. google may be a/b testing changes and collecting data. any other seo related changes to your site may be "re-spidering" and temporarily swaying rankings while the new data "settles in".

additionally, if you are viewing this in your personal browser on google, cookied information (i.e. you are logged into google) may be affecting personalization results which can mess with the order of competitive results.   location may be doing it to.

[Special]

Thanks Dan,

I doubt it'll be my browser as I've been really careful on that. The rest of what you've suggested all seems plausible to me but I'm curious to know how long major changes to a site related to SEO can take to settle-down. Should we do nothing and give it a week, or should we wait longer than that?