Computing the Z Score and Centiles for Cross-sectional Analysis: A Practical Approach.
Publication Title
Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine
Document Type
Article
Publication Date
3-1-2017
Keywords
california
Abstract
Although Z scores have been reported in the literature, one of the problems for the nonstatistician is understanding the systematic approach used to compute the predicted mean and standard deviation, components of the Z score equation, which may vary as the independent variable changes over time (eg, gestational age). This review focuses on a step-by-step analysis using linear, quadratic, and fractional polynomials to compute the mean and standard deviation as a function of a continuous independent variable. Once the mean and standard deviation are computed, the Z score and centile can be derived and Z score calculators created that enable investigators to implement the results in the laboratory and/or clinical setting.
Area of Special Interest
Women & Children
Area of Special Interest
Cardiovascular (Heart)
Specialty/Research Institute
Obstetrics & Gynecology
Specialty/Research Institute
Perinatology/Neonatology
Specialty/Research Institute
Diagnostic Imaging
DOI
10.7863/ultra.16.03025
