Use of Percentiles and Z-Scores in Anthropometry

  • Youfa WangEmail author
  • Hsin-Jen Chen


Percentiles and Z-scores are often used to assess anthropometric measures to help evaluate children’s growth and nutritional status. In this chapter, we first compare the concepts and applications of percentiles and Z-scores and their strengths and limitations. Compared to percentiles, Z-scores have a number of advantages: first, they are calculated based on the distribution of the reference population (mean and standard deviation), and thus reflect the reference distribution; second, as standardized quantities, they are comparable across ages, sexes, and anthropometric measures; third, Z-scores can be analyzed as a continuous variable in studies. In addition, they can quantify extreme growth status at both ends of the distribution. However, Z-scores are not straightforward to explain to the public and are hard to use in clinical settings. In recent years, there has been growing support to the use of percentiles in some growth and obesity references. We also discuss the issues related to cut point selections and outline the fitting/smoothing techniques for developing reference curves. Finally, several important growth references and standards including the previous and new WHO growth reference/standards and the US 2000 CDC Growth Charts, are presented and compared. They have been developed based on different principles and data sets and have provided different cut points for the same anthropometric measures; they could, thus, provide different results. This chapter will guide readers to understand and use percentiles and Z-scores based on recent growth references and standards.


Growth Standard Growth Chart Growth Reference International Obesity Task Force Percentile Curve 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



Body mass index


Centers for Disease Control and Prevention


International Obesity Task Force


Height- or length-for-age Z-score


Multicentre Growth Reference Study


National Center for Health Statistics


National Health and Nutrition Examination Survey


Standard deviation


World Health Organization


Weight-for-age Z-score



This work was supported in part by research grants from the NIH/NIDDK (R01DK81335-01A1, 1R03HD058077-01A1, R03HD058077-01A1S1) and the Nestle Foundation. We also thank Irwin Shorr for his ­comments on an earlier draft of this chapter.


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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  1. 1.Department of International HealthJohns Hopkins Bloomberg School of Public Health, Center for Human NutritionBaltimoreUSA

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