Estimating peak height velocity in individuals

Cole, Tim J.

doi:10.1080/03014460.2020.1837953

Cited by 3 publications

(2 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been suggested that PV values obtained with SITAR tend to be greater than those established with other population average models and cubic spline methodology, owing to the fact that the latter do usually not account for longitudinal data from a single individual (28).…”

Section: Comparing Sitar-based Results To Previous Investigations Of ...mentioning

confidence: 99%

Craniofacial growth and SITAR growth curve analysis

Patcas

Keller

Markic

et al. 2021

European Journal of Orthodontics

Self Cite

View full text Add to dashboard Cite

Summary Background SITAR (SuperImposition by Translation And Rotation) is a shape invariant growth curve model that effectively summarizes somatic growth in puberty. Aim To apply the SITAR model to longitudinal mandibular growth data to clarify its suitability to facial growth analysis. Subjects and methods 2D-cephalometric data on two mandibular measurements (AP: articulare–pogonion; CP: condylion–pogonion) were selected from the Denver Growth Study, consisting of longitudinal records (age range: 7.9–19.0 years) of females (sample size N: 21; number of radiographs n: 154) and males (N: 18; n: 137). The SITAR mixed effects model estimated, for each measurement and gender separately, a mean growth curve versus chronological age, along with mean age at peak velocity (APV) and peak velocity (PV), plus subject-specific random effects for PV and mean size. The models were also fitted versus Greulich–Pyle bone age. Results In males, mean APV occurred at 14.6 years (AP) and 14.4 years (CP), with mean PV 3.1 mm/year (AP) and 3.3 mm/year (CP). In females, APV occurred at 11.6 years (AP and CP), with mean PV 2.3 mm/year (AP) and 2.4 mm/year (CP). The models explained 95–96 per cent of the cross-sectional variance for males and 92–93 per cent for females. The random effects demonstrated standard deviations (SDs) in size of 5.6 mm for males and 3.9 mm for females, and SDs for PV between 0.3 and 0.5 mm/year. The bone age results were similar. Conclusion The SITAR model is a useful tool to analyse epidemiological craniofacial growth based on cephalometric data and provides an array of information on pubertal mandibular growth and its variance in a concise manner.

show abstract

Section: Comparing Sitar-based Results To Previous Investigations Of ...mentioning

confidence: 99%

Craniofacial growth and SITAR growth curve analysis

Patcas

Keller

Markic

et al. 2021

European Journal of Orthodontics

Self Cite

View full text Add to dashboard Cite

show abstract

“…There are several approaches to the estimation of individual trajectories and its derivatives for longitudinal data (see Boeyer et al, 2020;Cole, 2020;Malina et al, 2021, for a review of methods in the context of growth data). In the context of penalized regression models, where the function of interest is represented as a linear combination of basis functions (such as splines), the estimation of the derivative of the function is an immediate by-product of the fitted function.…”

Section: Introductionmentioning

confidence: 99%

Derivative curve estimation in longitudinal studies using P-splines

Hernández,

Lee,

Rodríguez-álvarez

et al. 2023

Statistical Modelling

View full text Add to dashboard Cite

The estimation of curve derivatives is of interest in many disciplines. It allows the extraction of important characteristics to gain insight about the underlying process. In the context of longitudinal data, the derivative allows the description of biological features of the individuals or finding change regions of interest. Although there are several approaches to estimate subject-specific curves and their derivatives, there are still open problems due to the complicated nature of these time course processes. In this article, we illustrate the use of P-spline models to estimate derivatives in the context of longitudinal data. We also propose a new penalty acting at the population and the subject-specific levels to address under-smoothing and boundary problems in derivative estimation. The practical performance of the proposal is evaluated through simulations, and comparisons with an alternative method are reported. Finally, an application to longitudinal height measurements of 125 football players in a youth professional academy is presented, where the goal is to analyse their growth and maturity patterns over time.

show abstract

Estimating peak height velocity in individuals: a response to Cole (2020)

Boeyer

Middleton

Duren

et al. 2020

Annals of Human Biology

View full text Add to dashboard Cite

Choosing a statistical methodology for modelling human growth is an important decision for researchers and clinicians alike. In Boeyer et al. (2020), we presented three common approaches for modelling childhood and adolescent growth (i.e. Natural Cubic Splines, SuperImposition by Translation and Rotation (SITAR), and Fifth Order Polynomials) with the primary aim to elucidate the advantages and disadvantages of each methodology. In a recent Letter to the Editor, Cole (2020) challenged two specific aspects of this work, including: (1) interpretations related to the derived "population average" and individual-level random effects in the SITAR methodology, and (2) our conclusions regarding the use of the polynomial methodology in paediatric clinical practice.Cole (2020) objects to our interpretation of the "population average" derived from the SITAR methodology, which we defined in our publication as the single curve derived from the data of all individuals combined. This definition is consistent with the documentation for the sitar () function, which states that "sitar is a methodology that summarises a set of growth curves with a mean growth curve as a regression spline." Given this language, the regression curve applied is approximating the mean or, using our terminology, "population" average trajectory.Cole (2020) also claims that Table 1 in Boeyer et al. ( 2020) "confirms that the SITAR mean curve is unbiased," because the values for PHV and aPHV derived from the "mean" or population average curve are the same as the mean estimate for all individuals included in our analyses. It is true that the average values we report for PHV and aPHV at both the population and individual level are not statistically different, but this specific comparison does not indicate the lack of "bias" within this methodology; instead, it highlights its shapeinvariant structure. To properly assess statistical bias, a cross-validation analysis is needed. In Boeyer et al. (2020), we performed a leave-one-out cross-validation analysis for each of

show abstract

Estimating peak height velocity in individuals

Cited by 3 publications

References 3 publications

Craniofacial growth and SITAR growth curve analysis

Craniofacial growth and SITAR growth curve analysis

Derivative curve estimation in longitudinal studies using P-splines

Estimating peak height velocity in individuals: a response to Cole (2020)

Contact Info

Product

Resources

About