Figure 7. The high variance of article and multinomial resampling can be estimated by a simple model that extends Possion resampling to account for papers that contribute multiple citations to the same journal.

A Average number of papers that contribute to a specific link weight in logarithmic scale. For all years, the number of papers with weight ( fits to the function with exponent . B The fraction of 1, 2, 3 and 4 citations that contribute to building a specific link weight . Compared to low link weights, high link weights have a lower fraction of papers with only one citation and a higher fraction of papers with 2, 3 or 4 citations. C The probability distribution of link weight for 4 cases: Poisson resampling, article resampling, multinomial resampling, and the minimal model. The high variance of article/multinomial resampling could be estimated by the model. D The model can generate higher variance than Poisson resampling for different link weights. However, it could not generate exactly as high a variance as article resampling.