ROBUST NON-PARAMETRIC ESTIMATION OF GENOTYPE–PHENOTYPE RELATIONSHIPS IN HUMAN PEDIGREES

Non‐parametric estimation of functional relationships is an important part of data analysis, particularly in the exploratory stages. This paper considers non‐parametric estimation of the mean functions in family studies using weighted robust estimating equations while retaining a fully parametric model for the covariance structure. The proposed procedure allows an exploratory examination of complex pedigree data that is an invaluable aid in determining appropriate models. This is illustrated by an examination of the relationship between IQ and the level of a particular protein in individuals collected as part of a large family study.     

A Comparison of Methods of Fitting Models to Twin Data

Data on twins are used to infer a genetic component of variance for various quantitative human characteristics. There are several statistical approaches available to analyze twin data. Here we compare three approaches for fitting variance components models to the relationship between height and bi-illiocristal diameter across ages in a sample of male and female Polish twins aged 8–17. Two of the approaches assume a multivariate normal model for the data, with one basing the likelihood on the raw data and the other using the distribution of the sample covariance matrix. The third approach uses a robust modification of the multivariate normal log-likelihood to downweight abnormal observations. The statistical theory underlying the methods is outlined, and the implementation of the methods is discussed.     

APPLICATIONS OF ROBUST ESTIMATION FOR VARIANCE COMPONENTS MODELS:THE DETECTION OF MAJOR GENE EFFECTS IN FINGER RIDGE COUNTS IN NORMAL AND FRAGILE X FAMILIES

A diagnostic technique is proposed to detect major gene effects and other systematic departures from a model for the trait means in the presence of outliers. The technique is based on the examination of residuals from fitting variance components models to quantitative pedigree data using robust statistical procedures. The approach is demonstrated using the total ridge count and ridge count of the middle finger from 54 extended families affected with the Fragile X syndrome, and a sample of 217 normal pedigrees.     

The Practice of Career Counseling by Specialists and Counselors in General Practice

This study sought to identify which career counseling work behaviors are unique to the specialty of career counseling and which career counseling work behaviors are an element of general counseling practice. Career counseling work behaviors related to assessment and counseling were judged to be fundamental to the general practice of counseling. Career counseling work behaviors related to program management, information, and consultation were judged to be fundamental to the specialty practice of career counseling. Implications for counselor certification and counseling program accreditation are discussed.