The table below shows the results of five independent studies on insider buying. It shows the investment returns generated from stocks showing significant insider buying compared to the general market. The only criteria in these studies was that two or more insiders bought company stock and that generally more insiders were buying then selling. I don't know what the hold period was in these studies, but I can safely guess were talking about months or years, instead of my favorite, minutes.
In any case, the edge that insider buying gives to stocks is what is important, and it's clearly set out below: