Why the Difference in Search Engine Rankings?

[airraid81]

I just checked my ranking for certain keywords on ranking check.com, and I have found some interesting discrepencies between sites. For example, for "Cadillac Williams hernia," I am #3 in Yahoo, but unranked in the others. For "Michael Vick dogfighting page," I am #9 in Google, but unranked in the others. I have been working hard to promote those two (and related) keywords, and I am just wondering how I can be so good in one search engine, but not even ranked in the others?

[Kevin]

Different search engines produce different rankings. They all use different algorithms and work in completely different ways to determine how results are placed. In theory its possible to be number 1 for a search term in one search engine and not even be listed in another

[caily]

Each search engines has different relevancy criteria used. each have different algo and different way on how search relevancy is calculated.

[annetokhien]

They're right. Different sites have different algorithms and criteria for ranking a site. You might rank 4 in Google and 5 in Yahoo. It also depends on how often these Search Engines update. How often they get a site crawled or indexed. :)

[Roguegal]

I'm just curious, is it possible to improve these rankings for all search engines at the same time? In other words, is it possible to get ranked #1 on all the search engines like Google or Yahoo? Even if they use this different systems or algorithms to determine placement, it seems like you would be able to do it.

[Dartz]

Quite a few of them filter out certain sites as well. I also think that a few give priority to certain sites when certain keywords are searched, like having the official page wind up as the first result.