Abstract

Semiparametric mixed model analysis benefits from variability estimates such as standard errors of effect estimates and variability bars to accompany curve estimates. We show how the underlying variance calculations can be done extremely efficiently compared with the direct naïve approach. These streamlined calculations are linear in the number of subjects, representing a two orders of magnitude improvement.

Highlights

  • A current vibrant area of research is the use of nonparametric regression, or smoothing, techniques in the analysis of longitudinal data

  • It consists of longitudinal measurements on the spinal bone mineral density (SBMD) of a cohort of young female subjects

  • The use of semiparametric regression in the analysis of longitudinal data has become commonplace in the last decade

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Summary

Introduction

A current vibrant area of research is the use of nonparametric regression, or smoothing, techniques in the analysis of longitudinal data. It consists of longitudinal measurements on the spinal bone mineral density (SBMD) of a cohort of young female subjects (source: Reference [9]). The key is recognition that the contribution to M from the random intercept component is an m × m diagonal matrix Such streamlining essentially removes computational obstacles involving variances for models such as (1) for most practical values of m and, greatly benefits semiparametric mixed model analysis.

Additive Mixed Models
Extension to Subject Specific Curves
Closing Remarks

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