Well, all of them.  However, the most important system is that we invest in people.  We invest in good companies.  We use technical analysis.  We have algorithms that point out stocks that are moving.  We listen to rumors.  We have built a sophisticated software based screener that runs all of the time scanning thousands of stocks in real time in order to narrow down what we are looking for.  In the end, we learn about the company, its managers, and its people.