Figure 1

Population distribution of various periods in three data sets. (a) Renren, the distribution of population size in 10th month (circle), 20th month (square), 30th month (star), 40th month (solid circle) and 50th month (triangle). Five curves are close to each other and seemingly follow the same distribution. The dashed line is the power law distribution: y ∼ x^-1.4. (b) Twitter, the distribution of population size in 8th month (circle), 18th month (square), 28th month (star), 38th month (solid circle) and 48th month (triangle). Five curves are close to each other and seemingly follow the same distribution. The dashed line is: y ∼ x^-1.78. (c) Gowalla, the distribution of population size in 5th month (circle), 10th month (square), 15th month (star) and 20th month (triangle). Four curves are close to each other and seemingly follow the same distribution. The dashed line is: y ∼ x^-1.4.