bear - 8:06 pm on May 30, 2007 (gmt 0)

The conclusion from your comments would appear to be that the reason a page goes supplemental is that the individual TBPR for that page is too low, below a threshold? say <2. This is simple. But if you look at the reasons put forward for a site having a large percentage of pages supplemental they often relate to the site. For example - too many duplicate pages, too many outward links, poor internal linkage structure, etc.

Halfdeck says

“If your site is largely supplemental, it means 1) not enough quality inbound links to your site 2) you have too many pages 3) you link out too much 4) Google may think your IBLs are artificial 5) Cannonical issues are causing PageRank to split.”

Sure you can translate these ‘site issues’ into an impact on the TBPR for each of the pages, but there is still reference to the ‘duplicate filter?’, low trust for the site, internal link structure, and other site wise penalties or issues?

The frustrating thing is that if I look at the pages that in the main index and compare them with ones that have gone supplemental there is no apparent difference between them: They are in a similar position in the hierarchy, they have unique content, they have the same number of unique words, they have been cached recently, etc., etc.,. Perhaps someone has linked to the individual pages that are in the main index, – but I don’t think so. The decision of what’s in and out appears to be arbitrary and if 50 are considered worthy of inclusion in the main index, why not include another 300 that should have essentially the same TBPR in terms of link structure, etc, etc. In my case it’s a travel site and each page for a town has a town description, holiday activities and lists of properties. Each page has unique meta info etc. I can't see what the difference is, and so I've nothing to work on. This was the reason for my impression that there was an arbitrary allocation – why include some but not others, when their features are identical. There's no common feature for the 'in' group, which would identify why they are 'in'. Perhaps it’s a penalty thing – but I’ve addressed all the issues I am aware of that may be causing this – no links to link farms etc. etc. Perhaps it’s a timing issue – maybe I should wait a few months and see what happens. Maybe the delays in response from Google, combined with my fiddling with things, are making it impossible to work out what’s happening. Or else focus on getting in bound links, including deep links to lift PR of the pages above the threshold for inclusion in the main index. It reminds me of trying to catch fish by 'thinking like a fish'- what bait, where, when. The Google system is a similar mystery - 'Thinking like the Googlebot' is another of life's frustrations! Particularly when the Google brain and system is for ever changing - at least the fish brains and thoughts are constant!