Responsiveness of quality of life instruments : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Statistics in Statistics at Massey University

Quality of life (QoL) is a phrase that is intuitively meaningful. As a concept it distinguishes between the mere duration of life and a life that is in some sense 'worthwhile'. QoL measurement is thought to be important in the assessment of chronic health conditions and their treatment. It is difficult to create an operational definition of QoL that takes into account different concepts of QoL as well as the heterogeneity of subjects and diseases. Responsiveness is one aspect of instruments which measure QoL. A responsive instrument captures the change in QoL in response to interventions which change underlying health conditions. Internal responsiveness, measured by a variety of standardised mean changes, reflects change in a QoL instrument score measured on subjects who 'should have' changed. External responsiveness relates change in a QoL instrument score to a change in external criteria. Methods of determining external responsiveness include receiver operating characteristic curves, correlation and simple regression. Simple linear regression can be extended using linear mixed models which can estimate parameters either by maximum likelihood or by Markov Chain Monte Carlo methods. This thesis critically examines methods of assessing responsiveness and demonstrates the methodology, including the extension to linear mixed models. The data set used for illustration is based on a study of subjects with rheumatoid arthritis who are assessed before and after a period of inpatient hospital treatment for their condition. Three new QoL instruments, the EuroQol, the Quality of Life Profile and the WHOQoL-Bref were found to be moderately responsive. However the available methodology and the extensions described in this thesis were unable to find any difference in responsiveness. Reasons for this could include that QoL instruments are relatively blunt instruments for the detection of change. The external criteria for change used may not have been ideal. The reasons for a choice of instrument for QoL assessment may be better related to ease of completion, interpretation and analysis, than on sophisticated assessment of responsiveness

A Brief Comment on Maxwell(/Newton)[-Huygens] Spacetime

I provide an alternative characterization of a "standard of rotation" in the context of classical spacetime structure that does not refer to any covariant derivative operator.Comment: 13 page

Categories and the Foundations of Classical Field Theories

I review some recent work on applications of category theory to questions concerning theoretical structure and theoretical equivalence of classical field theories, including Newtonian gravitation, general relativity, and Yang-Mills theories.Comment: 26 pages. Written for a volume entitled "Categories for the Working Philosopher", edited by Elaine Landr

Inertial motion, explanation, and the foundations of classical spacetime theories

I begin by reviewing some recent work on the status of the geodesic principle in general relativity and the geometrized formulation of Newtonian gravitation. I then turn to the question of whether either of these theories might be said to "explain" inertial motion. I argue that there is a sense in which both theories may be understood to explain inertial motion, but that the sense of "explain" is rather different from what one might have expected. This sense of explanation is connected with a view of theories---I call it the "puzzleball view"---on which the foundations of a physical theory are best understood as a network of mutually interdependent principles and assumptions.Comment: 41 pages, 2 figures. Invited for inclusion in Towards a Theory of Spacetime Theories, D. Lehmkuhl e

On the Status of the Geodesic Principle in Newtonian and Relativistic Physics

A theorem due to Bob Geroch and Pong Soo Jang ["Motion of a Body in General Relativity." Journal of Mathematical Physics 16(1), (1975)] provides a sense in which the geodesic principle has the status of a theorem in General Relativity (GR). I have recently shown that a similar theorem holds in the context of geometrized Newtonian gravitation (Newton-Cartan theory) [Weatherall, J. O. "The Motion of a Body in Newtonian Theories." Journal of Mathematical Physics 52(3), (2011)]. Here I compare the interpretations of these two theorems. I argue that despite some apparent differences between the theorems, the status of the geodesic principle in geometrized Newtonian gravitation is, mutatis mutandis, strikingly similar to the relativistic case.Comment: 16 page

Are Newtonian Gravitation and Geometrized Newtonian Gravitation Theoretically Equivalent?

I argue that a criterion of theoretical equivalence due to Clark Glymour [Nous 11(3), 227-251 (1977)] does not capture an important sense in which two theories may be equivalent. I then motivate and state an alternative criterion that does capture the sense of equivalence I have in mind. The principal claim of the paper is that relative to this second criterion, the answer to the question posed in the title is "yes", at least on one natural understanding of Newtonian gravitation.Comment: 27 page

On (Some) Explanations in Physics

I offer one possible explanation of why inertial and gravitational mass are equal in Newtonian gravitation. I then argue that this is an example of a kind of explanation that is not captured by standard philosophical accounts of scientific explanation. Moreover, this form of explanation is particularly important, at least in physics, because demands for this kind of explanation are used to motivate and shape research into the next generation of physical theories. I suggest that explanations of the sort I describe reveal something important about one way in which physical theories can be related diachronically.Comment: 32 pages. Forthcoming in Philosophy of Scienc