Time between SERP changes on Google

ultra-noob question

[pr0purgatory]

Here I display my complete ignorance about the process of making site changes and the time involved :)

Let's say I make a change to a page on my site that is intended to get it higher up the SERP food chain.

How long does Google take to pick up on the changes and move my site up or (hopefully not) down?

Is it when the cached page is refreshed?

Is it when Google crawls?

Only during solar eclipses?

[mipapage]

Super hard to tell. Sometimes when it's freshed, sometimes not. Ymmv, but these days I wait to see the alarm bells going off here before watching the serps.

When it does it shifts. I'm seeing three diff versions of serps for one client. They e-mail me each time it goes up, and each time it goes down... ;0]

[pr0purgatory]

Must be when the cache is refreshed. I changed my keywords for interest's sake and immediately dropped in rank for my old keywords when the cache refreshed.