The Stockopedia Insider Rank is a proprietary seven-factor model incorporating insider and senior director (board member) buying, cluster buying factors, net transaction values, net percentage position changes, relative percentage position changes, and short-term insider buying trends. Each factor is time-weighted to give extra weight to recent transactions.
Stocks that Rank highly on all these quantities will have high Insider Ranks; similarly, stocks that Rank badly will have low Insider Ranks.
You can read more about the Insider Rank here.