I want to compare own data with data generated by google analytics. For example I want to see the number of my twitter followers compared with my page visitors per day.
If you are willing to use Google Spreadsheets (which I can recommend) You can use a simple script to import your Analytics data automatically.
Here is a complete rundown of how to set it up: http://spreadsheetpro.net/how-to-import-google-analytics-data-into-google-spreadsheets-in-3-simple-steps/
Google Analytics supports many different Data Import use cases, which can be carried out both through the API and through Web Interface. You particular use case might not be supported currently, but perhaps you still could garner incites through some combination of the Measurement Protocol and User Data Import.
As far as I'm aware, it is not possible to import your own data into Google Analytics. You can however export data from Google Analytics and compare it with your own data in Open Office, Excel or another graphing solution.
Google Analytics - Data Export API - Java (v2) - http://analytics.blogspot.com/2009/08/analytics-data-in-excel-through-our-api.html
Google Analytics Blog - Analytics Data In Excel Through Our API - http://code.google.com/apis/analytics/docs/gdata/2.0/gdataJava.html
Google Analytics - How to export an Analytics Report - http://www.google.com/support/analytics/bin/answer.py?hl=en&answer=57161
SEOmoz - How to Export Google Analytics Data to Excel via the API - http://www.seomoz.org/blog/how-to-export-google-analytics-data-to-excel-via-the-api
You could write a script which runs daily on a server and connects to Twitter to measure the number of followers and then uploads the number of followers to Google Analytics. You could also report an event to Google Analytics when you get a new follower or when a follower unfollows you.
There are several options to upload data into Google Analytics:
1. Use a library which implements the ga.js script server-side
When you use Google Analytics in the way described by Google, you include a script on your website. This script sends data from the visitors browser to the Google Analytics server.
This script has been reverse engineered and implemented in server-side libraries. Now you can send the same data from the server to the Google Analytics server. You can use PHP-GA for PHP or pyga for Python.
2. Use the Google Analytics measurement protocol
The Google Analytics measurement protocol is a new API to send data to Google Analytics. You can send data by sending POST requests to the API.
Check out http://megalytic.com. You can download both Google Analytics and Twitter into the same Excel workbook. Handles Facebook, Omniture, and others as well.
For a high-level overview, you could use SWIX - I haven't tried it, but it allows you to make dashboards with input from a bunch of pre-generated sources, including Twitter, Facebook & GA. I suspect that you could build something similar with YouCalc as well, but it should work out of the box with SWIX.