Answering your question about if can Google Analytics track your data even when is not installed? the answer is NO, it can't
Let me explain my point
Understanding Google Analytics reports and capabilities requires an understanding of the basic principles. Knowing what data Google Analytics can capture and how it interprets it is key to making sense of the software.
At its most basic level, Google Analytics consists of
- JavaScript code on each page of a website,
- A data collection service on Google's servers
- A processing engine that creates report data
1. Google Analytics JavaScript Code
When a visitor arrives at a page with tracking code, the code is executed by his browser. It collects information about the visitor's browser and computer settings, like screen resolution, operating system, etc. The script's visibility is pretty limited. It can typically only see what it's told.
The script then sets a few cookies containing some basic visit information. These cookies determine whether it is a new or returning visitor, among other things.
2. Google Analytics Data Collection Service
Next, all of this information must be sent to the Google Analytics servers so it can be processed. The GA tracking code sends the information by requesting a very small file, named __utm.gif. It appends all the cookie data and information it just collected to the query string for __utm.gif. This way, Google's servers have a record of when a file was requested and all of the visitor information about that pageview.
Many organizations store a copy of every tracking request sent to the data collection service - this is accomplished with the setLocalRemoteServerMode(); function in ga.js. Once you have a local copy of Google Analytics tracking requests, you can process them with Angelfish Software and turn them into interactive reports.
3. Processing Visit Information
In the last step, Google Analytics processes all of the __utm.gif requests, applies filters and config settings, and makes the data available to your account.
Visit data is typically processed every few hours, although this frequency has been increasing over time. Google rolled out a set of Real Time data reports in 2011 although the data available in these reports is not comprehensive.
IN SUMMARY
If you don't have the script installed on your site, Google Analytics cannot track your website data. OF Course Im talking just about Google Analytics, because I'm sure that if we talk about Google (Search Engine) is another history