The analysis of change is an important issue in human growth and development. In longitudinal studies, growth patterns are often summarized by growth 'models' so that a small number of parameters, or the functions of them can be used to make group comparisons or to be related to other measurements. To analyse complete and balanced data, growth curves can be modelled using multivariate analysis of variance with an unstructured variance-covariance matrix; for incomplete and unbalanced data, models such as the two-stage model of Laird and Ware (1982) or the multilevel models of Goldstein (1987) are necessary. The use of multilevel models for describing growth is recognized as an important technique. It is an efficient procedure for incorporating growth models, either linear or nonlinear, into a population study. Up to now there is little literature concerning growth models over wide age ranges using multilevel models. The purpose of this study is to explore suitable multilevel models of growth over a wide age range. Extended splines are proposed, which extend conventional splines using the '+' function and by including logarithmic or negative power terms. The work has been focused on modelling human growth in length, particularly, height and head circumference as they are interesting and important measures of growth. The investigation of polynomials, conventional splines and extended splines on data from the Edinburgh Longitudinal Study shows that the extended splines are better than polynomials and conventional splines for this purpose. It also shows that extended splines are, in fact, piecewise fractional polynomials and describe data better than a single segment of a fractional polynomial. The extended splines are useful, flexible, and easily incorporated in multilevel models for studying populations and for the estimation and comparison of parameters.

Darbe tirti 1990 metais gimusių Vilniaus miesto ir rajono vaikų augimo ypatumai nuo gimimo iki brendimo pabaigos, individualių raidos takų įvairovė, etniniai, socialiniai ir ekonominiai augimo veiksniai, „nepriklausomybės kartos“ vaikų fizinės būklės epochiniai pokyčiai ir augimo tendencijos. Šis darbas – vienas pirmųjų mūsų šalies auksologinių tyrimų, kuriame buvo nustatyta vaikų augimo takų individuali įvairovė nuo gimimo iki aštuoniolikos metų amžiaus. Šiame longitudiniame 1990 m. (atgavus Lietuvos nepriklausomybę) gimusių vaikų tyrime buvo naudojamas ambulatorinių kortelių metodas, ištirti jo privalumai ir trūkumai. Nustatyta, kad profilaktinių vaikų apsilankymų poliklinikoje dažnis susijęs su vaiko amžiumi, gyvenamąja vieta (miestas arba kaimas), atstumu iki poliklinikos ir vaiko gimimo eiliškumu. Vaikų augimo rodiklių įrašai ambulatorinėse kortelėse palyginti tikslūs ir tinkami auksologinei analizei. Darbo rezultatai patvirtino, kad ūgio ir kūno masės indekso raidos takų kaita augimo laikotarpiu yra normalus reiškinys, priklauso nuo amžiaus ir lyties. Po 1990 m., t.y. didelių politinių, socialinių ir ekonominių pertvarkų laikotarpiu vaikų fizinių rodiklių augimas atsiliko palyginus su stabiliais šalies raidos laikotarpiais. Neigiami šio laikotarpio vaikų augimo pokyčiai buvo grįžtami. Nustatyti etniniai ir socialiniai abiejų lyčių vaikų fizinės būklės skirtumai. Pagrindiniai vaikų fiziniai rodikliai (ūgis, svoris, kūno masės indeksas) per pastaruosius dešimtmečius... [toliau žr. visą tekstą] / Physical status of children born in 1990 in Vilnius city and region from birth up to the end of puberty, the variety of individual growth tracks, ethnic and socio-economic growth factors, the epochal changes in growth and growth patterns of the “generation of independence” were investigated. This study was one of the first to establish the variety of individual growth tracks from birth to the age of eighteen years. In this longitudinal study of children born in 1990 (the year Lithuania restored its independence) the personal health records’ analysis was used and its benefits and drawbacks were investigated. The age of children, the place of residence (urban or rural), the distance to the outpatient clinic and the ordinal number of a child in a family were associated with the regularity of visiting the outpatient clinic. Children's growth indices in personal health records were rather accurate and suitable for auxological analysis. The results of this study confirmed that children normally changed their growth tracks for height and body mass index during the growth process. These changes were associated with their age and sex. Retardation in growth of children was related to the political and socioeconomic changes in Lithuania after 1990. Nevertheless, this retardation was reversible. Ethnic and socioeconomic differences in physical status of both boys and girls were established. The main body size indices (height, weight and body mass index) of children remained almost... [to full text]

This dissertation attempts to integrate the household and children more fluidly into measures of well-being in the past. In part one, I develop a Monte Carlo simulation to test some of the assumptions of Allen’s welfare ratio methodology. These included his assumptions that family size was constant over time, that there were no female-headed households and that women and children did not participate in the labour force. After all of the adjustments, it appears that Allen’s welfare ratios underestimate the welfare ratios of a demographically representative group of families, especially if women and children’s labour force participation is included. However, the predicted distributions also highlight the struggles of agricultural labourers, who are given separate consideration. Even the average agricultural labourers’ family with women and children working would have had to rely of self- provisioning, gleaning, poor relief or the extension of the working year to make ends meet at the poorest point in their family life cycle. Part two adjusts Floud et al.’s estimates of calorie availability in the English economy from 1700 to 1909 for the costs of digestion, pregnancy and lactation. Taken together, these three additional costs reduced the amount calories available by around 15 per cent in 1700 but only by 5 per cent in 1909 because of the changing composition of the English diet. Part three presents a new adaptive framework for studying changes in children’s growth patterns over time and a new methodology, longitudinal growth studies, for measuring gender disparities in health in the past. An adaptive framework for understanding growth provides a more parsimonious explanation for the vast catch-up growth achieved by slave children in the antebellum American South. The slave children were only able to achieve this catch-up growth because they were programmed for a tall height trajectory by relatively good conditions in utero. Finally, impoverished girls experienced greater catch-up growth than boys in two schools in late-nineteenth century Boston, USA and early-twentieth century London, suggesting that girls were deprived relative to boys before entering these institutions.