I'm predicting a large Google algorithm change this weekend or next

I created a little tool for myself that helps me track keywords that I'm optimizing on, and the websites associated with those optimization campaigns. This is a tool used offline, and I have to enter data into it manually. It works well when gauging the progress of some of my optimization campaigns. I wrote it myself using Visual Basic 6, and it has some nifty features.

One thing I use it for is to track keywords that I no longer perform optimization for. The SERPs for these keywords are fairly stable, moving up and down through the various Google dance steps. In general, they trend down, simply because I no longer focus on them. I can generally tell when Google is testing an algo tweak because these keywords bounce around in the SERPs then settle back to roughly their same previous positions.

I created a formula based on these keywords (there are about 100 of them) that shows the variance in SERPs over time. The formula produces a number that gives me a basic idea of the current volatility of the Google search results. The number can be anywhere between -100 and 100, with zero being absolutely no change from the previous week (I normally manually add the updated SERP data once per week, but the formula will work equally well on a daily, hourly, monthly, or yearly basis. The shorter the time period, however, the more pronounced are any small changes.)

Normally, the variance figure is between 5-10 (or -5 and -10), which means a variance of 5-10. (*Note-I'm not a math whiz, so if my terminology is incorrect, you know where you can take yourself). During some of the obvious algo tweaks, the variance goes as high as 15 or 20, but usually drops after one week. Since the formula uses about 100 keywords, a severe change for one keyword doesn't alter the end result as severely as it would were I only to use 5 or 6 keywords. When the variance hits 15 or 20, that means that I've had some fairly significant change in SERPs for my keywords. The change may be up or down because the direction of the SERP change isn't as important to me as the actual amount of increase or decrease.

Two weeks ago, I started entering SERP values in as often as possible (often once per day). I've been paying close attention to the variance looking for signs that Google is doing algo testing. Twice in the last two weeks, I've seen major SERP changes that showed variances of up to 35. Even factoring in the changes introduced by doing it nearly daily, that shows at least a minor algo change has taken place. My opinion is that those were instances of Google nerds testing algo changes in preparation for a larger algorithm change.

I may just be reading the tea leaves incorrectly, but I'm expecting the algorithm changes that have been tested over the last month or so to be implemented either this weekend or next. If it doesn't happen this weekend, and next week is fairly quiet regarding SERP movements, watch out - we may be in for a major algorithm change.

(For those who are going to ask the obvious question: no I don't see a toolbar PR update happening for quite a while still.)