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BioMed Research International
Volume 2014, Article ID 790294, 5 pages
Research Article

Using Skew-Logistic Probability Density Function as a Model for Age-Specific Fertility Rate Pattern

1Department of Statistics, Amirkabir University of Technology, Tehran 15875-4413, Iran
2College of Information Science Technology, University of Nebraska-Omaha, Omaha, NE 68182, USA

Received 4 February 2014; Revised 13 April 2014; Accepted 27 April 2014; Published 21 May 2014

Academic Editor: Stefano Curcio

Copyright © 2014 Sahar Asili et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Fertility rate is one of the most important global indexes. Past researchers found models which fit to age-specific fertility rates. For example, mixture probability density functions have been proposed for situations with bi-modal fertility patterns. This model is less useful for unimodal age-specific fertility rate patterns, so a model based on skew-symmetric (skew-normal) pdf was proposed by Mazzuco and Scarpa (2011) which was flexible for unimodal and bimodal fertility patterns. In this paper, we introduce skew-logistic probability density function as a better model: its residuals are less than those of the skew-normal model and it can more precisely estimate the parameters of the model.