Similar title to Westlund, A., Ermolieva, T.Y., & MacKellar, F.L. (2000). Analysis and forecasting of social security: A study of robustness. In: Financial Modeling. Eds. Bonilla, M., Casasus, T., & Sala, R., Heidelberg: Physica-Verlag. ISBN 3-7908-1282-X