20,922 research outputs found
Common scale valuations across different preference-based measures: estimation using rank data
Background: Different preference-based measures (PBMs) used to estimate Quality Adjusted Life Years (QALYs) provide di¤erent utility values for the same patient. Differences are expected since values have been obtained using different samples, valuation techniques and descriptive systems. Previous studies have estimated the relationship between pairs of PBMs using patient self-reported data. However, there is a need for an approach capable of generating values directly on a common scale for a range of PBMs using the same sample of general population respondents and valuation technique but keeping the advantages of the different descriptive systems.
Methods: General public survey data (n=501) where respondents ranked health states described using subsets of six PBMs were analysed. We develop a new model based on the mixed logit to overcome two key limitations of the standard rank ordered logit model, namely, the unrealistic choice pattern (Independence of Irrelevant Alternatives) and the independence of repeated observations.
Results: There are substantial differences in the estimated parameters between the two models (mean di¤erence 0.07) leading to di¤erent orderings across the measures. Estimated values for the best states described by di¤erent PBMs are substantially and significantly di¤erent using the standard model, unlike our approach which yields more consistent results.
Limitations: Data come from a exploratory study that is relatively small both in sample size and coverage of health states.
Conclusions: This study develops a new, �exible econometric model specifically designed to reflect appropriately the features of rank data. Results support the view that the standard model is not appropriate in this setting and will yield very different and apparently inconsistent results. PBMs can be compared using a common scale by implementation of this new approach
Dissipation in Mesoscopic Superconductors with Ac Magnetic Fields
The response of mesoscopic superconductors to an ac magnetic field is
investigated both experimentally and with numerical simulations. We study small
square samples with dimensions of the order of the penetration depth. We obtain
the ac susceptibitity at microwave frequencies as a
function of the dc magnetic field . We find that the dissipation, given
by , has a non monotonous behavior in mesoscopic samples. In the
numerical simulations we obtain that the dissipation increases before the
penetration of vortices and then it decreases abruptly after vortices have
entered the sample. This is verified experimentally, where we find that
has strong oscillations as a function of in small squares of
Pb.Comment: 4 pages, 2 figure
Probing the ZZgamma and Zgammagamma Couplings Through the Process e+e- --> nu anti-nu gamma
We study the sensitivity for testing the anomalous triple gauge couplings
and via the process
at high energy linear colliders. For integrated luminosities of 500
and center of mass energies between 0.5 and 1.5 , we find that this
process can provide tests of the triple neutral gauge boson couplings of order
, one order of magnitude lower than the standard model prediction.Comment: 12 pages, 6 figure
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