Before revision: In domains with power law tails, sample measures of top centile contributions to the total (concentration) are  biased, unstable estimators  extremely sensitive to both unit and sample size and concave in accounting for large deviations.
After revision: In domains with power law tails, sample measures of top centile contributions to the total (concentration) are downward biased, unstable estimators extremely sensitive to both unit and sample size and concave in accounting for large deviations.