Ranking Models in Conjoint Analysis

In this paper we consider the estimation of probabilisticranking models in the context of conjoint experiments. By usingapproximate rather than exact ranking probabilities, we do notneed to compute high-dimensional integrals. We extend theapproximation technique proposed by \\citet{Henery1981} in theThurstone-Mosteller-Daniels model for any Thurstone orderstatistics model and we show that our approach allows for aunified approach. Moreover, our approach also allows for theanalysis of any partial ranking. Partial rankings are essentialin practical conjoint analysis to collect data efficiently torelieve respondents' task burden.conjoint experiments;partial rankings;thurstone order statistics model

Confidence intervals for maximal reliability of probability judgments

Subjective probabilities play an important role in marketingresearch, for example where individuals rate the likelihood thatthey will purchase a new to develop product. The tau-equivalentmodel can describe the joint behaviour of multiple test itemsmeasuring the same subjective probability. It improves thereliability of the subjective probability estimate by using aweighted sum as the outcome of the test rather than an unweightedsum. One can choose the weights to obtain maximal reliability.In this paper we stress the use of confidence intervals to assessmaximal reliability, as this allows for a more critical assessmentof the items as measurement instruments. Furthermore, two newconfidence intervals for the maximal reliability are derived andcompared to intervals derived earlier in \\citet{YuanBentler2002,RaykovPenev2006}. The comparison involves coverage curves, amethodology that is new in the field of reliability. The existingYuan-Bentler and Raykov-Penev intervals are shown to overestimatethe maximal reliability, whereas one of our proposed intervals, thestable interval, performs very well. This stable interval hardlyshows any bias, and has a coverage for the true value which isapproximately equal to the confidence level.confidence intervals;subjective probability;coverage curves;maximal reliability;measurement scales;tau-equivalent model

Analyzing preferences ranking when there are too many alternatives.

Consumer preferences can be measured by rankings of alternatives. When there are too many alternatives, this consumer task becomes complex. One option is to have consumers rank only a subset of the available alternatives. This has an impact on subsequent statistical analysis, as now a large amount of ties is observed. We propose a simple methodology to perform proper statistical analysis in this case. It also allows to test whether (parts of the) rankings are random or not. An illustration shows its ease of application

Confidence intervals for maximal reliability of probability judgments

Subjective probabilities play an important role in marketing research, for example where individuals rate the likelihood that they will purchase a new to develop product. The tau-equivalent model can describe the joint behaviour of multiple test items measuring the same subjective probability. It improves the reliability of the subjective probability estimate by using a weighted sum as the outcome of the test rather than an unweighted sum. One can choose the weights to obtain maximal reliability. In this paper we stress the use of confidence intervals to assess maximal reliability, as this allows for a more critical assessment of the items as measurement instruments. Furthermore, two new confidence intervals for the maximal reliability are derived and compared to intervals derived earlier in \\citet{YuanBentler2002, RaykovPenev2006}. The comparison involves coverage curves, a methodology that is new in the field of reliability. The existing Yuan-Bentler and Raykov-Penev intervals are shown to overestimate the maximal reliability, whereas one of our proposed intervals, the stable interval, performs very well. This stable interval hardly shows any bias, and has a coverage for the true value which is approximately equal to the confidence level

Ranking Models in Conjoint Analysis

In this paper we consider the estimation of probabilistic ranking models in the context of conjoint experiments. By using approximate rather than exact ranking probabilities, we do not need to compute high-dimensional integrals. We extend the approximation technique proposed by \\citet{Henery1981} in the Thurstone-Mosteller-Daniels model for any Thurstone order statistics model and we show that our approach allows for a unified approach. Moreover, our approach also allows for the analysis of any partial ranking. Partial rankings are essential in practical conjoint analysis to collect data efficiently to relieve respondents' task burden

Schwinger-Keldysh Approach to Disordered and Interacting Electron Systems: Derivation of Finkelstein's Renormalization Group Equations

We develop a dynamical approach based on the Schwinger-Keldysh formalism to derive a field-theoretic description of disordered and interacting electron systems. We calculate within this formalism the perturbative RG equations for interacting electrons expanded around a diffusive Fermi liquid fixed point, as obtained originally by Finkelstein using replicas. The major simplifying feature of this approach, as compared to Finkelstein's is that instead of $N \to 0$ replicas, we only need to consider N=2 species. We compare the dynamical Schwinger-Keldysh approach and the replica methods, and we present a simple and pedagogical RG procedure to obtain Finkelstein's RG equations.Comment: 22 pages, 14 figure

Effect of extended cefquinome treatment on clinical persistence or recurrence of environmental clinical mastitis

The effectiveness of antibiotic treatment of clinical mastitis (CM) is classically evaluated using bacteriological cure, which provides a concise and objective way of assessing efficacy but does not reflect the situation in the field where persistence or recurrence of clinical signs lead to perceived treatment failure. If clinical signs persist or recur, intramammary (IMM) treatment is often extended or supplemented with parenteral therapy in the expectation of a more efficient elimination of clinical signs or a lower probability of recurrence. The objective of this study was to evaluate the efficacy against clinical persistence or recurrence of three cefquinome treatment regimes, standard 1.5-day intramammary (SIMM), 5-day extended intramammary (EIMM) and combination of EIMM plus 5-day extended parenteral (ECOMBO) treatment. The study was conducted on three dairy farms with a high recurrence rate of environmental mastitis. Efficacy was evaluated using a multi-level model at the quarter and at the cow level, based on the persistence or recurrence of clinical signs at any time during a 105-day period following the end of the initial treatment, independent of pathogen. The most prevalent pathogens were E. coli (16.9%) and S. uberis (11.97%). EIMM and ECOMBO significantly decreased the persistence or recurrence of CM by 8% and 6% at the quarter level and by 9% and 8% at the cow level, respectively. ECOMBO may not reduce the persistence or recurrence of CM beyond EIMM. Whilst extended treatment regimens offered an improved outcome in this study, the producer and practitioner need to carefully consider such regimens from the perspective of prudent antibiotic use

The effects of non-universal extra dimensions on the radiative lepton flavor decays \mu\to e\gamma and \tau\to \mu\gamma in the two Higgs doublet model

We study the effect of non-universal extra dimensions on the branching ratios of the lepton flavor violating processes \mu\to e\gamma and \tau\to \mu\gamma in the general two Higgs doublet model. We observe that these effects are small for a single extra dimension, however, in the case of two extra dimensions there is a considerable enhancement in the additional contributions.Comment: 16 Pages, 9 Figure

A meta-analysis on the diagnostic performance of whole-body MRI for the initial staging of Hodgkin lymphoma in children and adults using FDG-PET/CT as a reference standard

Background: Staging of Hodgkin lymphoma is important for determining prognosis and treatment planning. The current gold standard is FDG-PET/CT, but WB-MRI could be a radiation free alternative. Objective: A meta-analysis of all published data on the diagnostic performance of WB-MRI for the initial staging of Hodgkin lymphoma using FDG-PET/CT as a reference standard. Evidence Acquisition: Both the PubMed/MEDLINE and EMBASE databases were systematically searched (updated until March 14, 2023) for studies that compared WB-MRI with FDG-PET/CT for staging Hodgkin lymphoma. The “quality assessment of diagnostic accuracy studies” tool (QUADAS-2) was used to assess methodological quality. Pooled staging accuracy, sensitivity and specificity of WB-MRI compared to FDG-PET/CT was calculated for determining stage and for both nodal and extra-nodal staging. A sensitivity analysis for children and adults was performed. Evidence Synthesis: A total of nine studies with a combined total of 297 Hodgkin lymphoma patients were included. Pooled sensitivity and specificity for nodal staging were 94% (95%CI 0.92–0.96) and 99% (95%CI 0.98–1.00) respectively. For extra-nodal staging sensitivity and specificity were 90% (95%CI 0.74–0.96) and 100% (95%CI 0.99–1.00). For disease stage, the pooled accuracy was 92% for pediatric studies (95%CI 0.86–0.96), 94% for adult studies (95%CI 0.87–0.97) and 92% (95%CI 0.87–0.96) for all studies combined. Conclusion: When using FDG-PET/CT as a reference standard, WB-MRI shows high sensitivity and specificity for both nodal and extra-nodal staging and for determining disease stage both in children and adults. Clinical Impact: WB-MRI could be used as a good radiation-free alternative for FDG-PET/CT in Hodgkin lymphoma staging

Applications of patching to quadratic forms and central simple algebras

This paper provides applications of patching to quadratic forms and central simple algebras over function fields of curves over henselian valued fields. In particular, we use a patching approach to reprove and generalize a recent result of Parimala and Suresh on the u-invariant of p-adic function fields, for p odd. The strategy relies on a local-global principle for homogeneous spaces for rational algebraic groups, combined with local computations.Comment: 48 pages; connectivity now required in the definition of rational group; beginning of Section 4 reorganized; other minor change