Let's say you buy a domain that was a previously established website...

[Kventures]

...

 

[Theo]

It would lose 50% of its results after 2 or 3 Google refresh cycles, if it were a forum.
For domains with static pages, it takes longer.

 

[Kventures]

...

 

[Theo]

This, is the $64,000 question
I would say 3 months per cycle.

 

[Kventures]

...

 

[Theo]

If it's a type-in you'll be getting these results consistently. It really depends on the number of backlinks and whether these are updated, e.g. from an index/portal or from forum posts, from static page web sites etc.

 

[simon johnson]

It really depends on the domain name. You can reasonably expect all the pages to get dropped from the index over time. However some domains (particularly those well publicized) tend to get dropped entirely from the index.

Backlinks from other sites tend to hang around (again it depends on the site). However, to give you a rough estimate, around 2002 I redirected a domain name to an existing website. I still have 2000+ backlinks to that domain.

 

[CyrusL]

Both of these posts are wrong and gross oversimplifications of the modern algorithm:

It would lose 50% of its results after 2 or 3 Google refresh cycles, if it were a forum.
For domains with static pages, it takes longer.

There's not much in the Google algorithm that one can assign percentage points to like "50% of it's results." Moreover, rank for competitive high-volume keywords is much more important than simply the volume of indexed results. I have sites that have thousands of indexed results and they don't get as much traffic or make as much money as some of my sites with ten pages and great rank.

This, is the $64,000 question
I would say 3 months per cycle.

Google crawls my popular sites several times a day and my unpopular sites a couple times a month. Big ranking changes are happening all the time and there is absolutely no major multi-month cycle for it. Pagerank does take months to change but these days PR is completely meaningless. Even the infamous Google sandbox doesn't last 3 months for most domains.

Rob, if you want some sources for legitimate SEO discussion send me a PM and I will try to help you out. I'm much more into the paid search side of things but I can point you in the right direction.

FYI, response time, backlinks, content, and coding are all taken into account for the algorithm. I would try to get some SE-friendly content up there as soon as possible or 301 redirect the traffic somewhere that does so you can salvage some rank while you can. It depends a lot on the site, but if you're willing to put some time into your content, you'll get a much bigger payoff than giving the site up to a parked page.

 

[Theo]

"Oversimplification" is quite applicable when no specified domain is posted. Additionally, your algorithm analysis relies on your own portfolio; which again is an overly-simplified sample of the millions of domains available. Unless you can quote specific Google FAQ's of course.

 

[CyrusL]

Additionally, your algorithm analysis relies on your own portfolio; which again is an overly-simplified sample of the millions of domains available.

I gave examples of my own sites as counter-examples of your posts. They illustrate the pointlessness of anecdotal evidence in the modern algorithm. Thus, there is a need for legitimate, testable, and verifiable SEO knowledge; not posts like "50% of it's results every 3 refresh cycles."

 

[Theo]

Mine's a quote of accumulated results. The bigger the sampler, the better. I own a large number of old domains, pre-2000, and thus I can testify to the accuracy of my quote.

 

[nametrader]

In my sense SEO is a commonsense, whatever algorithms search engines have they mainly look at usability, originality amongst other things. If you are able to trick a search engine and get on to top you are an SEO expert! whether the trick works permanently or bombs in short span depends on skill level. No matter what SEO we do search engines do their job of indexing reindexing updating etc they have cycles, in between we do tricks and succeed because it takes time for a Search engine to look back at the SEO Expert, if it were a Human it will slap on the face right away so the delay and cycles in this whole gigantic process leaves loop holes here and there we all take advantage of.

To the original poster if you do a original creation irrespective of prior history of the domain you will be a winner, if you put a minisite that self updates like crazy with tons of duplicate content, your domain is going to loose rankings and eventually die.

My 2 cents.