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.
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