PPC_Chris - 8:20 pm on Jul 1, 2011 (gmt 0)

The way my ranking dropped, it looks like Google demoted all pages on my entire site by xx%. This wouldn't mean that all pages drop the same amount in ranking or traffic goes down by xx%... let me explain what I mean.

Let's say for each search query Google assigns a value to every ranked page. For simplicity, this value is 100 for the top result. Consider the following examples:

Keyword 1 (highly competitive)
Rank 1: 100
Rank 2: 80
Rank 5: 70
Rank 10: 50
Rank 100: 25

Keyword 2 (long tail term)
Rank 1: 100
Rank 2: 50
Rank 5: 20
Rank 10: 10
Rank 100: 2

Keyword 3 (branded term, "yourdomain.com")
Rank 1: 100
Rank 2: 10
Rank 5: 5
Rank 10: 2
Rank 100: 1


Now consider that Panda imposed a 50% penalty on your domain, you can see that depending on your ranking and the value Google assigns to you and your competitors this could drop your rankings tremendously... while an equally penalized page will not appear to be penalized at all (think of ranking #1 on your branded terms).

This is what I see with my Panda penalty... for brands-specific terms we are still in # 1 position - sitelinks and all with 0% loss in traffic. For our most competitive terms where we compete head to head loads of sites, our rankings took a huge hit with 90%+ loss in traffic. For less popular terms, where we compete with only a handful of sites, we dropped modestly and lost about 50% of traffic.

My theory is that the Panda penalty had the most effect on pages that Google considers to be close in value (in Google's algorithm) to the pages below in the SERPs.