This article introduces the new 5-level EQ-5D (EQ-5D-5L) health status measure. EQ-5D currently measures health using three levels of severity in five dimensions. A EuroQol Group task force was established to find ways of improving the instrument's sensitivity and reducing ceiling effects by increasing the number of severity levels. The study was performed in the United Kingdom and Spain. Severity labels for 5 levels in each dimension were identified using response scaling. Focus groups were used to investigate the face and content validity of the new versions, including hypothetical health states generated from those versions. Selecting labels at approximately the 25th, 50th, and 75th centiles produced two alternative 5-level versions. Focus group work showed a slight preference for the wording 'slight-moderate-severe' problems, with anchors of 'no problems' and 'unable to do' in the EQ-5D functional dimensions. Similar wording was used in the Pain/Discomfort and Anxiety/Depression dimensions. Hypothetical health states were well understood though participants stressed the need for the internal coherence of health states. A 5-level version of the EQ-5D has been developed by the EuroQol Group. Further testing is required to determine whether the new version improves sensitivity and reduces ceiling effects.

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Development and preliminary testing of the new five-level version of EQ-5D (EQ-5D-5L)

Various methods for determining unidimensionality are reviewed and the rationale of these methods is as sessed. Indices based on answer patterns, reliability, components and factor analysis, and latent traits are reviewed. It is shown that many of the indices lack a rationale, and that many are adjustments of a previous index to take into account some criticisms of it. After reviewing many indices, it is suggested that those based on the size of residuals after fitting a two- or three-parameter latent trait model may be the most useful to detect unidimensionality. An attempt is made to clarify the term unidimensional, and it is shown how it differs from other terms often used inter changeably such as reliability, internal consistency, and homogeneity. Reliability is defined as the ratio of true score variance to observed score variance. Inter nal consistency denotes a group of methods that are intended to estimate reliability, are based on the vari ances and the covariances of test items, and depend on on...

/pdf/methodology-review-assessing-unidimensionality-of-tests-and-8z19v63f5v.pdf

Methodology review: Assessing unidimensionality of tests and items

A conceptual framework employing the distinction between stimulus-centered and subject-centered scales is presented as a basis for reviewing 80 years of literature on the optimal number of response...

The optimal number of response alternatives for a scale: A review.

Objective The feasibility, reliability, and validity of a new instrument, the MacArthur Competence Assessment Tool-Treatment (MacCAT-T), which was developed for use by clinicians, was tested. The instrument assesses patients' competence to make treatment decisions by examining their capacities in four areas--understanding information relevant to their condition and the recommended treatment, reasoning about the potential risks and benefits of their choices, appreciating the nature of their situation and the consequences of their choices, and expressing a choice. Method The MacCAT-T and instruments to measure symptom severity were administered to 40 patients recently hospitalized with schizophrenia or schizoaffective disorder and 40 matched subjects in the community without mental illness. Results A high degree of ease of use and interrater reliability was found for the MacCAT-T. Overall, the hospitalized patients performed significantly more poorly than the community subjects on understanding and reasoning, although many patients performed as well as community subjects. Poor performance was related to higher levels of some psychiatric symptoms, such as conceptual disorganization, hallucinations, and disorientation. Conclusions The MacCAT-T offers a flexible yet structured method with which caregivers can assess, rate, and report patients' abilities relevant for evaluating competence to consent to treatment.

The MacCAT-T: a clinical tool to assess patients' capacities to make treatment decisions.

Correspondence analysis is an exploratory data analysis technique for the graphical display of contingency tables and multivariate categorical data. Its history can be traced back at least 50 years...

Correspondence Analysis: Graphical Representation of Categorical Data in Marketing Research:

One of the most contentious issues in medical and legal practice is how to reliably assess the mental competence of individuals who consent or refuse psychiatric treatment. Current legislation does not provide clear definitions of what constitutes competence or incompetence to make a treatment decision. As a preliminary attempt to operationalize the concept of competency, we have developed a 15 item questionnaire. The present study reports on the psychometric properties of the instrument. Test-retest and interrater reliability results were good. The instrument was internally consistent and discriminated between individuals found competent and incompetent by the treating physician.

The psychometric properties of the Competency Interview Schedule.

This study formulates a property of a quantification method, the principle of equivalent partitioning (PEP). When the PEP is used together with Guttman's principle of internal consistency (PIC) in a simple way, the combination offers an interesting way of analyzing categorical data in terms of the variate(s) chosen by the investigator, a type of canonical analysis. The study discusses applications of the technique to multiple-choice, rank-order, and paired comparison data.

Forced classification: A simple application of a quantification method

A modified technique of separable programming was used to maximize the squared correlation ratio of weighted responses to partially ordered categories. The technique employs a polygonal approximation to each single-variable function by choosing mesh points around the initial approximation supplied by Nishisato's method. The major characteristics of this approach are: (i) it does not require any grid refinement; (ii) the entire process of computation quickly converges to the acceptable level of accuracy, and (iii) the method employs specific sets of mesh points for specific variables, whereby it reduces the number of variables for the separable programming technique. Numerical examples were provided to illustrate the procedure.

Nonlinear programming approach to optimal scaling of partially ordered categories

Multidimensional Nonlinear Descriptive Analysis

Some historical background and preliminary technical information are first presented, and then a number of hidden, but important, methodological aspects of dual scaling are illustrated and discussed: normed versus projected weights, the amount of information accounted for by each solution, a perfect solution to the problem of multidimensional unfolding, multidimensional quantification space, graphical display, number-of-option problems, option standardization versus item standardization, and asymmetry of symmetric (dual) scaling. Contrary to the common perception that dual scaling and similar quantification methods are now mathematically transparent, the present study demonstrates how much more needs to be clarified for routine use of the method to arrive at valid conclusions. Data analysis must be carried out in such a way that common sense, intuition and sound logic will prevail.

Shizuhiko Nishisato

Papers

The psychometric properties of the Competency Interview Schedule.

Forced classification: A simple application of a quantification method

Nonlinear programming approach to optimal scaling of partially ordered categories

Multidimensional Nonlinear Descriptive Analysis

Gleaning in the field of dual scaling