Preference Measurement Techniques Research Articles

Optimized stereo digital image correlation setup for miniature round specimen: framework development and implementation

For the advancement of micro- and nano-technologies, multiaxial material testing at a small length scale is imperative. A novel multiaxial miniature testing system (MMTS) is under development for testing a tubular specimen of outer diameter (OD) as small as 1 mm. Because of the small specimen size of MMTS, stereo-Digital Image Correlation (DIC) is the preferred strain measurement technique. Although theoretically, stereo-DIC is length-scale independent, the implementation of stereo-DIC, particularly for miniature testing, faces experimental setup related challenges. For this reason, although stereo-DIC is strongly recommended over 2D DIC, researchers are sometimes compelled to use the latter. It is shown in the present study that the experimental setup related difficulties, particularly for miniature round specimen testing, can be overcome by a systematic development of a mathematical framework for stereo-DIC implementation. This framework addresses all setup decisions concerning stereo-DIC implementation, such as selections of stereo angle, speckle size, camera position, camera sensor size, lens focal length, dimensions of camera and lens bodies, calibration grid size, etc., as well as stereo-DIC analysis parameters, such as subset and step size. Besides serving the need of building a stereo-DIC setup for MMTS, since the developed mathematical framework treats all stereo-DIC setup decisions as variables, it can be used to develop an optimized stereo-DIC setup for any application. Examples of two general cases are reported. Since this general framework serves as a tool to solve the stereo-DIC experimental setup related challenges, the developed framework will contribute to the wider adoption of stereo-DIC over 2D DIC.

A Simplified Measure of Investor Risk Aversion

This article introduces a simplified measure of investor risk aversion. The singleitem question combines elements from revealed preference and propensity measurement techniques in a way that matches traditional constant relative risk-aversion estimation procedures. Based on survey data from 500 investors living in the United States, scores from the proposed measure were found to correlate with other measures of risk aversion, as well as with indicators of risk-taking. A validity test showed that answers to the proposed measure were statistically associated with equity and cash ownership holdings in respondent portfolios. The simplicity and intuitive nature of the proposed measure and the alignment of question response categories to estimates of constant relative risk aversion make this a potentially valuable addition to the toolkit of researchers, financial educators, investors and those who provide advice to investors.JEL: C83, D10, D11, D14, D19, D81

Methods to Assess Patient Preferences in Old Age Pharmacotherapy - A Systematic Review.

PurposeThe aim of this systematic review was to identify methods used to assess medication preferences in older adults and evaluate their advantages and disadvantages with respect to their applicability to the context of multimorbidity and polypharmacy.Material and MethodsThree electronic databases (PubMed, Web of Science, PsycINFO) were searched. Eligible studies elicited individual treatment or outcome preferences in a context that involved long-term pharmacological treatment options. We included studies with a study population aged ≥ 65 years and/or with a mean or median age of ≥ 75 years. Qualitative studies, studies assessing preferences for only two different treatments, and studies targeting preferences for life-sustaining treatments were excluded. The identified preference measurement methods were evaluated based on four criteria (time budget, cognitive demand, variety of pharmacological aspects, and link with treatment strategies) judged to be relevant for the elicitation of patient preferences in polypharmacy.ResultsSixty articles met the eligibility criteria and were included in the narrative synthesis. Fifty-five different instruments to assess patient preferences, based on 24 different elicitation methods, were identified. The most commonly applied preference measurement techniques were “medication willingness” (description of a specific medication with inquiry of the participant’s willingness to take it), discrete choice experiments, Likert scale-based questionnaires, and rank prioritization. The majority of the instruments were created for disease-specific or context-specific settings. Only three instruments (Outcome Prioritization Tool, a complex intervention, “MediMol” questionnaire) dealt with the broader issue of geriatric multimorbidity. Only seven of the identified tools showed somewhat favorable characteristics for a potential use of the respective method in the context of polypharmacy.ConclusionUp to now, few instruments have been specifically designed for the assessment of medication preferences in older patients with multimorbidity. To facilitate valid preference elicitation in the context of geriatric polypharmacy, future research should focus on suitable characteristics of existing techniques to develop new measurement approaches for this increasingly relevant population.

An integrated hierarchical survey for a large-scale conjoint study for mobile phones

Recent trends in the mobile phone industry have significantly influenced the application of multi-attribute preference measurement techniques (conjoint analysis). As mobile phones become more complex and as consumers become more informed about a large number (10 or more) of product attributes in developed and emerging countries, the aim of this study – to reduce the number and complexity of the questions asked of the consumer – has led the authors to propose an integrated hierarchical survey design to be used with the Kano model for large-scale conjoint analysis. This method was used to determine the high utility levels of the key attributes of mobile phones in a mature and emerging market. The results of this study were successfully implemented for product planning, product development and marketing by a mobile phone company through utilization of the results to set prices, prioritize features and provide guidelines for selecting target market segments.

New Opportunities in Mid-Infrared Emission Control.

Tunable laser absorption spectroscopy (TLAS) has been well accepted as a preferred measurement technique for many industrial applications in recent years, especially for in situ applications. Previously, mainly near-infrared lasers have been used in TLAS sensors. The advent of compact mid-infrared light sources, like quantum cascade lasers and interband cascade lasers, has made it possible to detect gases with better sensitivity by utilizing fundamental absorption bands and to measure species that do not have any absorption lines in the near-infrared spectral region. This technological advancement has allowed developing new sensors for gases, such as nitric oxide and sulfur dioxide, for industrial applications. Detection limits of better than 1 ppm · m for nitric oxide and better than 10 ppm · m for sulfur dioxide are demonstrated in field experiments.

On the influence of context-based complexity on information search patterns: An individual perspective.

Although context-based complexity measured as the similarity and conflict across alternatives is dependent on individual preference structures, existing studies investigating the influence of context-based complexity on information search patterns have largely ignored that context-based complexity is user- and preference-dependent. Addressing this research gap, this article elicits the individual preferences of decision makers by using the pairwise-comparison-based preference measurement (PCPM) technique and records individuals??? search patterns using eye tracking. Our results show that an increased context-based complexity leads to an increase in information acquisition and the use of a more attribute-wise search pattern. Moreover, the information search pattern changes within a choice task as information is processed attribute-wise in earlier stages of the search process and alternative-wise in later ones. The fact that we do not find an interaction effect of context-based complexity and decision stages on the search patterns indicates that the influence of complexity on search patterns stays constant throughout the decision process and suggests that the more complex the choice task is, the later the switch from attribute-wise strategies to alternative-wise strategies will be.

Perceptual and Physiological Responses to Jackson Pollock's Fractals.

Fractals have been very successful in quantifying the visual complexity exhibited by many natural patterns, and have captured the imagination of scientists and artists alike. Our research has shown that the poured patterns of the American abstract painter Jackson Pollock are also fractal. This discovery raises an intriguing possibility – are the visual characteristics of fractals responsible for the long-term appeal of Pollock's work? To address this question, we have conducted 10 years of scientific investigation of human response to fractals and here we present, for the first time, a review of this research that examines the inter-relationship between the various results. The investigations include eye tracking, visual preference, skin conductance, and EEG measurement techniques. We discuss the artistic implications of the positive perceptual and physiological responses to fractal patterns.

Physics, perception, and physiological of Jackson Pollock's fractals

Fractals have experienced considerable success in quantifying the visual complexity exhibited by many natural patterns and have captured the imagination of scientists and artists alike. Our research has shown that the poured patterns of the American abstract painter Jackson Pollock are also fractal. This discovery raises an intriguing possibility—are the visual characteristics of fractals responsible for the long-term appeal of Pollock's work? To address this question, we have conducted ten years of scientific investigation of human response to fractals and here we present, for the first time, a review of this research that examines the inter-relationship between the various results. The investigations include eye-tracking, visual preference, skin conductance, EEG and preliminary fMRI measurement techniques. We discuss the artistic implications of the positive perceptual, physiological, and neurological responses to fractal patterns.

Cascade Impactor (CI) Mensuration—An Assessment of the Accuracy and Precision of Commercially Available Optical Measurement Systems

Multi-stage cascade impactors (CIs) are the preferred measurement technique for characterizing the aerodynamic particle size distribution of an inhalable aerosol. Stage mensuration is the recommended pharmacopeial method for monitoring CI "fitness for purpose" within a GxP environment. The Impactor Sub-Team of the European Pharmaceutical Aerosol Group has undertaken an inter-laboratory study to assess both the precision and accuracy of a range of makes and models of instruments currently used for optical inspection of impactor stages. Measurement of two Andersen 8-stage 'non-viable' cascade impactor "reference" stages that were representative of jet sizes for this instrument type (stages 2 and 7) confirmed that all instruments evaluated were capable of reproducible jet measurement, with the overall capability being within the current pharmacopeial stage specifications for both stages. In the assessment of absolute accuracy, small, but consistent differences (ca. 0.6% of the certified value) observed between 'dots' and 'spots' of a calibrated chromium-plated reticule were observed, most likely the result of treatment of partially lit pixels along the circumference of this calibration standard. Measurements of three certified ring gauges, the smallest having a nominal diameter of 1.0 mm, were consistent with the observation where treatment of partially illuminated pixels at the periphery of the projected image can result in undersizing. However, the bias was less than 1% of the certified diameter. The optical inspection instruments evaluated are fully capable of confirming cascade impactor suitability in accordance with pharmacopeial practice.

Measuring Preferences for Really New Products

The goal of this research is to improve preference measurement for really new products. An initial assumption validated in the first study is that consumers have greater uncertainty when estimating the usefulness of really new products than they have with incremental new products. Consumers cope with this uncertainty by using certain inferential techniques that are not well captured by standard preference measurement techniques, such as conjoint. This research examines techniques for incorporating both mental simulation and analogies into an existing preference measurement technique and shows that some methods enhance and other methods hinder predictive accuracy.

Ionized Calcium or Corrected Total Calcium?

To the Editor: We would like to respond to the Letter of Larsson and Magnusson.1 In the Statement summarizing the deliberations of the Panel that was convened after the National Institutes of Health Workshop on the Management of Asymptomatic Primary Hyperparathyroidism,2 we recommended corrected total serum calcium over ionized serum calcium concentration as the preferred measurement technique. Larsson and Magnusson argue that the ionized serum calcium, the physiologically activity moiety of the circulating calcium concentration, should be preferred over the total calcium measurement. In their letter, they correctly point out variability in the algorithms by which the total calcium value is corrected for the prevailing albumin concentration. They also believe that ionized calcium measurement technology is readily available in hospitals these days, and finally, that the total serum calcium concentration is not without its own standardization problems. We certainly agree with their latter point, and in the Summary Statement, make a plea for greater uniformity and consistency with regard to the normal range of the total serum calcium concentration. We also acknowledge differences in the algorithms by which the total serum calcium is corrected for the prevailing albumin concentration. However, the Panel felt that these points do not argue yet for a change from the corrected total calcium concentration to the ionized calcium concentration because the ionized calcium test still requires a procedural and technical rigor that is greater than that required for the measurement of the total serum calcium concentration. Some centers have successfully instituted such measures, and can therefore, rely on the ionized calcium, but for most hospitals and reference laboratories in the United States, this is not yet the case. We are mindful that certain countries such as Sweden, have overcome the limitations of the ionized calcium to a greater extent than has the United States. In those countries, certainly one would opt for the ionized calcium concentration. However, the Panel addressed itself to issues in the United States, being careful to point out that our recommendations may not be applicable to other countries. In the United States, all things considered at this time, the Panel feels that the corrected total serum calcium concentration is the preferred measurement over the ionized calcium concentration.

Cost effectiveness of microwave thermotherapy in patients with benign prostatic hyperplasia: part I—methods

Objectives. To present the method used to evaluate the cost effectiveness, from the societal perspective, of transurethral microwave thermotherapy relative to medical therapy (alpha-blocking agents) and transurethral resection of the prostate (TURP) for a hypothetical cohort of 65-year-old men with moderate-to-severe benign prostatic hyperplasia (BPH) symptoms. Methods. We constructed a decision-analytic Markov model with 25 health states describing the 3 treatments, 5 short-term clinical events, and 17 possible long-term outcomes. Each health state had an associated cost and utility. Utility weights, reflecting an individual’s preference for a specific health outcome, range from 0, indicating death, to 100, indicating perfect health. Utility estimates were obtained by interviewing 13 men with moderate-to-severe BPH symptoms using the standard gamble preference measurement technique. On the basis of their risk attitudes, the patients were classified as risk averse or non-risk averse. The rates of remission, temporary and permanent adverse events, retreatment, and mortality were obtained from the Targis System (Urologix) randomized clinical trial, published reports, and a consensus panel. The costs during the 5 years after treatment initiation were estimated using national Medicare reimbursement schedules. The costs are reported in 1999 U.S. dollars. Results. Eliciting utility values from patients with BPH was feasible and generated internally consistent and externally valid measures. In the non-risk-averse group, the utility value for significant remission, moderate remission, no remission, and worsening BPH symptoms without an adverse event was 99.1, 97.1, 94.4, and 87.3, respectively. As expected, the risk-averse individuals (n = 6) exhibited higher utility values than those in the non-risk-averse group (n = 7). In the non-risk-averse group, thermotherapy was the preferred treatment, and in the risk-averse group, medical therapy was preferred. In both groups, TURP was the least preferred therapy. The initial thermotherapy procedure costs without complications were estimated at $2629, and the initial TURP procedure costs without complications were estimated at $4597. Time-dependent probabilities were developed to reflect treatment durability. Conclusions. The resulting model parameters appear to be suitable for evaluating the cost effectiveness of thermotherapy relative to medical therapy and TURP in 65-year-old men with moderate-to-severe BPH symptoms.

Understanding quality-adjusted life years and their application to pharmacoeconomic research.

To provide a basic overview of quality-adjusted life years (QALYs) and their application in cost-effectiveness analysis (CEA), compare and contrast QALYs with other health-related quality-of-life (HRQOL) assessments, describe current controversies regarding QALYs, and provide comparisons between QALY instruments. The literature regarding HRQOL and QALYs was reviewed and key issues are summarized. QALYs provide relative preferences of patients for different health states. They range from 0, representing death, to 1.0, representing optimal health. QALYs are distinguished from other HRQOL assessments in that they provide a summary measurement that incorporates quantity of life in addition to HRQOL. When QALYs are used as the outcome measure in CEA, a cost per QALY is calculated. The Panel on Cost Effectiveness in Health and Medicine has recommended that QALYs be used as outcome measures in CEA; when QALYs are used in CEA, comparisons between treatments for different illnesses as well as within an illness are possible. The three most commonly used preference measurement techniques in determining QALYs are visual analog scales, time trade-off, and standard gamble. Controversies regarding QALYs include which preference measurement technique is most appropriate, whether QALY assessments should be obtained from patients or the community, and how to address states, such as coma, that individuals sometimes assess as worse than death. QALY instruments can be compared regarding preference measurement technique, HRQOL domains assessed, ease of administration, validity, reliability, and sensitivity. When used appropriately, QALYs provide valuable outcome measures for pharmacoeconomic research.

Self-Perceived Health Status and Health-Related Quality of Life of Extremely Low-Birth-Weight Infants by Adolescence

Objectives. —To estimate and to compare the self-assessed health status and health-related quality of life of extremely low-birth-weight (ELBW) and control infants during adolescence. Design. —Prospective, observational study of an inception cohort with a concurrent control group. Setting. —Geographically defined region in central-west Ontario. Participants. —We interviewed 141 (83%) of 169 ELBW survivors born between 1977 and 1982 and 124 (86%) of 145 controls aged between 12 and 16 years. In addition, proxy responses obtained from parents were used for 9 severely impaired teenagers. Main Outcome Measures. —Assessments of health status (6 attributes), measured with the Health Utilities Index Mark 2 classification system, and health-related quality of life (utilities), quantified with 2 preference measurement techniques, were used to quantify each participant's self-reported, subjectively defined health state and 4 preselected hypothetical health states. Results. —Adolescents who were ELBW infants reported a higher number of attributes affected, as well as more complex and severe limitations in cognition, sensation, self-care, and pain, compared with controls. Statistically significant differences for the teenagers' health-related quality of life were noted between ELBW and control teenagers in the mean utility scores (0.87±0.26 vs 0.93±0.111;P=.02 on a conventional scale where 0=dead and 1.00=perfect health). However, a similar percentage of ELBW and control teenagers (71% vs 73%) gave utility ratings of more than 0.95 for their health status. Conclusions. —Direct measures of self-reported health status and utility scores indicated that, as a cohort, adolescents who were ELBW infants suffer from a greater burden of morbidity and rate their health-related quality of life as significantly lower than control teenagers. Nevertheless, the vast majority of ELBW respondents view their health-related quality of life as quite satisfactory and are difficult to distinguish from controls.

Self-perceived Health Status and Health-Related Quality of Life of Extremely Low-Birth-Weight Infants at Adolescence

To estimate and to compare the self-assessed health status and health-related quality of life of extremely low-birth-weight (ELBW) and control infants during adolescence. Prospective, observational study of an inception cohort with a concurrent control group. Geographically defined region in central-west Ontario. We interviewed 141 (83 percent) of 169 ELBW survivors born between 1977 and 1982 and 124 (86 percent) of 145 controls aged between 12 and 16 years. In addition, proxy responses obtained from parents were used for 9 severely impaired teenagers. Assessments of health status (6 attributes), measured with the Health Utilities Index Mark 2 classification system, and health-related quality of life (utilities), quantified with 2 preference measurement techniques, were used to quantify each participants self-reported, subjectively defined health state and 4 preselected hypothetical health states. Adolescents who were ELBW infants reported a higher number of attributes affected, as well as more complex and severe limitations in cognition, sensation, self-care, and pain, compared with controls. Statistically significant differences for the teenagers' health-related quality of life were noted between ELBW and control teenagers in the mean utility scores (0.87 +/- 0.26 vs 0.93 +/- 0.11; P=.02 on a conventional scale where O=dead and 1.00=perfect health). However, a similar percentage of ELBW and control teenagers (71 percent vs 73 percent) gave utility ratings of more than 0.95 for their health status. Direct measures of self-reported health status and utility scores indicated that, as a cohort, adolescents who were ELBW infants suffer from a greater burden of morbidity and rate their health-related quality of life as significantly lower than control teenagers. Nevertheless, the vast majority of ELBW respondents view their health-related quality of life as quite satisfactory and are difficult to distinguish from controls.

Patient preferences in surgery for scoliosis.

To assess individual preferences for a method of scoliosis surgery, we surveyed 224 teen-age patients, their parents, orthopaedic surgeons, and other health professionals. Rather than asking the respondents directly for the relative importance that they would assign to the four possible outcomes, we employed conjoint analysis, a preference measurement technique that is widely used in marketing and psychology. In conjoint analysis, respondents explicitly trade off the relative desirability of certain aspects of the outcome of scoliosis surgery--for example, between greater degree of curve correction or greater risk of reoperation. This study indicated that risk of nerve damage had the highest relative importance to the respondents, followed by risk of reoperation, curve correction, and aftercare, in that order. This ranking was found in all five groups of respondents.

X-ray absorption spectrometry as a tool for the study of molecular structure

X-ray absorption spectroscopy is a relatively new tool for the investigation of electronic structure and the local environment of specific atoms in biological molecules. Until recently, these techniques were not practical for the low concentrations required in biological preparations. With the development of high flux X-ray beams produced by synchrotrons, much interest has been generated in development of its application to biological problems. It is a unique tool in that it probes only the local environment of specific atoms and is not limited by the physical state of the sample ( e.g., gases, liquids, solids, solutions, gels, etc.). Unlike X-ray diffraction, the entire structure of a crystal need not be solved to obtain information concerning the structure of the active site of a molecule. In these respects, X-ray absorption spectroscopy is ideally suited for biologically problems. It has grown enormously as a practical technique since the opening of the Stanford Synchrotron Radiation Laboratory in 1974. In many biological systems the active sites include one or more transition metal atoms. In most cases, however, the metal atoms are very dilute and are responsible for only a small part of the total absorption. Fluorescence detection is usually the preferred measurement technique, and one is often forced to work with spectra of less than ideal signal-to-noise quality. Mathematical techniques have been developed to extract information from this type of experimental data. A further complication is that care must be taken to avoid X-ray damage of the biological samples. EXAFS(extented X-ray absorption fine structure) experiments have been performed on a large number of macromolecules of interest to biochemistry. These experiments can roughly be divided into two groups. The first involves proteins where the ligands of the metal ion are already known from diffraction, and EXAFS is used to obtain more accurate bond length and geometry information. The second group of experiments deals with proteins where some or all of the ligands are unknown, and the goal is to determine the coordination number, the bond lengths, and ultimately the local structure. In both these groups model compounds play an important role in aiding the analysis and establishing confidence in the results. Absorption features below the K X-ray absorption edge of 3 d transition metal complexes can be assigned, in sufficiently sites, to transitions from the 1 s orbital to vacant 3 d, 4 s, and 4 p orbitals. The spacing between these levels can be perturbed from those obtaining in the analogous free ion states since the vacant orbitals are hybridized with the filled orbitals of ligand atoms, leading to antibonding orbitals of elevated energy. This hybridization is, of course, quite different for the d, s, and p orbitals as they are of quite different sizes and symmetries. A study of a number of Cu(I) and Cu(II) complexes shows that the 1 s → 4 s and 1 s → 4 p ranges of observed energies of the features of the two charge states partly overlap, indicating that effects of covalency outweigh effects of valency itself. In addition, there are multiple scattering modes in this region of the spectrum which, if properly interpreted, can give information on the local structure around the metal atom. Series of metal-ligand complexes in which the total charge state is changed while keeping the ligand atoms constant show how these atomic and scattering features depend on local structure. Several examples of metalloproteins studied by the Bell Laboratories group will be described.

Size determination of Streptococcus mutans 10499 by laser light scattering

We have performed three different optical experiments to determine the mean size of the bacterial strain Streptococcus mutans 10449, a microorganism with dimensions comparable to the wavelength of the light used in our experiments. The three optical measurements give size values which are consistent with one another and favorably comparable to the consistency we found in identical measurements on a test system of polystyrene spheres of dimensions similar to the bacteria. Homodyne time correlation and power spectrum spectroscopy both depend on the coherence and monochromaticity of laser light for the determination of the mean diffusion coefficient of the scatterers. The Stokes-Einstein equation then relates the diffusion constant to the cell size. Differential light scattering relies for the interpretation of experimental data on the classical theoretical analysis of the angular distribution of scattered light from a scattering object. The three methods yield mean values for the radius of S. mutans 10499 of 0.324 +/- 0.006 mum, 0.0325 +/- 0.007 mum, and 0.315 +/- 0.009 mum, respectively. However, since intensity correlation spectroscopy provides a direct measure of polydispersity, it would appear to be the preferred single measurement technique for size determination.

Consumer Preference Judgments: An Exposition with Empirical Applications

The modeling of preferences for multiattribute alternatives has received an increased attention in marketing (consumer behavior) and management science (decision analysis). The research in the two disciplines is closely related and can be applied to predicting consumer preferences for multiattribute options. The purpose of this paper is to illustrate and discuss several preference models and measurement techniques that have been used mainly by decision analysts and which are applicable in the consumer preference judgment context. A pilot application of the measurement techniques which provides some insight on their relative predictive accuracy and on the usefulness of empirically verifying the conditions necessary for the existence of the preference models is reported, too.