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This article presents a procedure for generating a sequence of data sets which will yield exactly the same fitted simple linear regression equation y = a + bx. Unless rescaled, the generated data sets will have progressively smaller variability for the two variables, and the associated response and covariate will "regress" towards their unconditional sample means. (Contains 5 figures and 1 table.)

This paper reports on a principal component factor analysis of the SF-36 health status questionnaire in the three major ethnic groups in New Zealand (New Zealand Europeans, Maori and Pacific). The SF-36 is hypothesised to have a two-dimensional structure with distinct (weakly correlated) mental and physical health components, and support for this structural model has generally been found cross-nationally. However, in Maori and Pacific models of health mental and physical dimensions are not generally seen as separable, or independently functioning. This raises the possibility that the questionnaire's hypothesised structural model would not be supported among Maori and Pacific ethnic groups. This study evaluated that possibility. The results of the analysis showed a similar factor structure among New Zealand Europeans, and younger Maori (<45 years) to that reported by Ware et al. for Western European countries. Among Pacific people and older Maori (45 years and over), however, the factor structure did not clearly differentiate physical and mental health components. Implications are discussed both specific to the SF-36 (and in particular the use of principal component summary scores), and more generally for the cross-cultural validity of self-reported health status measures.

Objective: To assess the acceptability, reliability and validity of the SF-36 health survey in the New Zealand population and provide key population norms., Method: The SF-36 questionnaire was part of the 1996/97 New Zealand health survey, a cross-sectional, nationally representative survey of 7,862 adults (15 years and over)., Results: Overall, in the New Zealand population the questionnaire performed as well as or better than in other national surveys, but there was variability in data completeness across subgroups, and responses were skewed towards the healthy end of the scales. Males scored higher than females on almost all scales; increasing age was associated with decreasing scores (with the exception of the mental health scale); and New Zealand Europeans tended to report better health than the other ethnic groups., Conclusions: Satisfactory psychometric performance was demonstrated for the SF-36 in the New Zealand population, but researchers need to find ways of increasing data completeness in population groups shown here to have lower completion rates. The questionnaire may be better at discriminating patient rather than population subgroups. The SF-36 normative data confirm in kind, if not in degree, population subgroup disparities in health status observed using objective measures., Implications: Overall, the SF-36 questionnaire appears to be a valid and reliable measure of health-related quality of life for the New Zealand population. However, this paper highlights issues for researchers using the SF-36, such as the skewed nature of responses obstained in a population sample.

Objective: To develop a noninvasive method to detect disaccharide malabsorption in dogs by measuring hydrogen concentration ([H2]) in exhaled breath before and after experimentally induced disaccharide malabsorption., Animals: 8 healthy mixed-breed dogs., Procedure: [H2] was measured every 30 minutes for 8 hours after administration of disaccharide solutions (lactose, 0.5 g/kg of body weight; lactose, 1.0 g/kg; sucrose, 2.0 g/kg; maltose, 1.5 g/kg; and lactose [0.5 g/kg] and sucrose [2.0 g/kg]) to determine reference ranges of [H2] for each solution, which were compared with [H2] in dogs with experimentally induced disaccharide malabsorption. To induce disaccharide malabsorption, dogs were given a mild overdose of lactose (1.5 g/kg) or a disaccharidase inhibitor. In the latter experiment, acarbose (10 mg/kg, PO) was given with the combination of lactose (0.5 g/kg) and sucrose (2 g/kg), and with maltose (1.5 g/kg)., Results: Overdosing with lactose resulted in [H2] persistently outside the reference range for lactose in 5 of 8 dogs. Acarbose administration resulted in [H2] persistently outside the reference range in 7 of 8 dogs that received a combination of sucrose and lactose but did not consistently affect [H2] after administration of maltose., Conclusions: Disaccharide malabsorption resulted in [H2] outside the reference ranges in most of the adult dogs studied, suggesting that the technique may be useful in detecting naturally occurring disaccharidase deficiency.

The present retrospective study was designed to explore the question of whether or not ego identity status transition pathways and change rates differ significantly across domains of identity development from adolescence through middle adulthood. A sample of 100 middle- and upper-middle-class New Zealand adults from forty to sixty-three years of age were interviewed regarding the development of values in the areas of vocation, religion, politics, and gender roles, and relationships using an adaptation of the Marcia Ego Identity Status Interview. Raters later assigned an identity status for each year of chronological age for each participant. Preliminary analyses indicated that subgroups of the larger sample differed significantly in terms of identity status transition patterns. Within each of the eight subgroups examined, there were statistically significant differences in transition pathways and change rates across the five identity domains. These findings suggest the importance of examining separate identity domains and controlling for demographic variables in future studies of adult identity development. Results are discussed in terms of Grotevant's process model of identity formation.