What is a p-factor in descriptive statistics when looking at research articles. I'm looking at 3 studies. 1. A meta- Analysis by L Franco...Anticoagulation in patients with isolated distal deep vein thrombosis: a meta-analysis. 2. A meta-analysis by George Kirkilesis...Treatment of distal deep vein thrombosis and 3. Thrombolytic strategies versus standard anticoagulation for acute deep vein thrombosis of the lower limb. What is the p-factor in each of these studies and how is a p-factor obtained?