Market Effects of Sponsored Search Auctions

We investigate the market effects of brand search advertising, within a model where two firms simultaneously choose the price of their (differentiated) product and the bids for the advertising auction which is triggered by own and rival’s brand keywords search; and where there exist sophisticated/attentive consumers (who look for any available in-formation on their screen) and naive/inattentive consumers (who only look at the top link of their screen), both aware of either brand’s characteristics and price. Relative to a benchmark where only organic search exists, in any symmetric equilibrium each firm wins its own brand auction, and advertising has detrimental effects on welfare: (i) the sponsored link crowds out the rival’s organic link, thus reducing competition and choice, and leading to price increases; (ii) the payment of the rival’s bid (may) raise marginal cost, also contributing to raise market prices. Under extreme asymmetry (there is an incumbent and an unknown new entrant), we do find that the market effect of brand bidding might be beneficial, if the search engine does not list the entrant’s link in organic search, and the share of the sophisticated consumers in the economy is large enough for an equilibrium in which the entrant wins the advertising auction on the search for the incumbent’s brand to exist

Rasch-Built Measure of Pleasant Touch through Active Fingertip Exploration

Background: Evidence suggests that somatic sensation has a modality for pleasant touch. Objective: To investigate pleasant touch at the fingertip level (i.e., glabrous skin site) through the elaboration of a linear unidimensional scale that measures (i) various materials according to the level of pleasantness they elicit through active fingertip explorations and (ii) subjects according to their pleasantness leniency levels. Subjects: We enrolled 198 healthy subjects without any neurological disease. Methods: Blindfolded subjects actively explored 48 materials with their index fingertips and reported the perceived pleasantness of each on a 4-level scale. The fingertip moisture levels on each subject were measured before the experimental session. Data were analyzed using the Rasch model. Results: We elaborated unidimensional linear scale that included 37 materials according to their pleasantness of touch. The pleasantness level of 21 materials was perceived differently, depending on the fingertip moisture levels of the subjects. Conclusion: Based on our findings, we formulated a Pleasant Touch Scale. Fingertip moisture levels appeared to be a major factor for (un)pleasant feelings during active exploration

ABILHAND: a Rasch-built measure of manual ability in upper limb impaired patients

Thèse de doctorat en sciences biomédicales (SBIM 3)--UCL, 200

Functional assessment in physiotherapy. A literature review.

The present literature review on functional assessment in physiotherapy was carried out for the following reasons: 1) to identify the functional instruments used in the field of physiotherapy that were supported by published evidence of their psychometric qualities; 2) to investigate how these instruments relate to the International Classification of Functioning, Disability and Health (ICF); and 3) to investigate the use of functional instruments in the financing of physiotherapy. A search of Medline from 1990 to December 2005, in the domains of functional evaluation, psychometric qualities, functional classification, and health policy in relation to physiotherapy resulted in a list of 1,567 studies. Two reviewers examined the resulting references on the basis of their title and abstract, in order to select the studies that presented data on the psychometric qualities of functional evaluation tests, leading to a final selection of 44 such studies. A selection of functional tests was identified in four major diagnostic groups treated in community physiotherapy: musculoskeletal disorders (including lower back pain), stroke, the elderly, and traumatic brain injuries. The functional tests authors identified essentially cover the body and activities dimension of the ICF. The selected tests could be used as a basis for the standardisation of functional evaluation of the major diagnostic groups treated in community physiotherapy. This means that standards are available for reporting and following the evolution of patients both longitudinally and transversally. Nevertheless, in the current literature review no attempt at using functional outcomes as a rationale for financing physiotherapy could be found to date

Développer et interpréter une échelle de mesure. Applications du modèle de Rasch

Les questionnaires d'évaluation sont les instruments les plus utilisés aujourd'hui dans le domaine de la médecine et des sciences humaines pour évaluer des variables telles que l'incapacité physique, l'altruisme ou la douleur. Pourtant les praticiens connaissent souvent mal ces instruments. Que mesurent-ils vraiment ? Comment les résultats doivent-ils être interprétés ? Le présent ouvrage s'efforce de répondre à ces questions. Il ne s'agit pas d'un simple mode d'emploi des questionnaires d'évaluation. Son objectif principal est de fournir à tous, chercheurs et praticiens, les bases méthodologiques nécessaires pour développer un tel instrument et pour en interpréter les résultats. Après avoir exposé les fondements d'une mesure objective formulés par le modèle de Rasch, les auteurs adressent une série de questions fréquemment posées dans leur contexte d'application. Quels sont les critères d'une mesure objective ? Les résultats peuvent-ils être interprétés de manière quantitative ? Comment valider un tel instrument de mesure ? Peut-on comparer les réponses observées chez différents groupes de sujets ? Six chapitres, agrémentés de nombreux exemples pratiques et d'exercices résolus, exposent les bases méthodologiques de l'évaluation quantitative à l'aide du modèle de Rasch. Le septième chapitre décrit, pas à pas, les étapes du développement et de la validation d'une échelle de mesure de l'habileté manuelle

Outcome evaluation of the hand and wrist according to the International Classification of Functioning, Disability, and Health.

This article is a brief review of the outcome evaluation of the hand and wrist according to the International Classification of Functioning, Disability, and Health. Several tools currently exist to quantify outcome in hand surgery at the impairment level (eg, mobility, hand strength, cutaneous sensation, dexterity). According to the World Health Organization's paradigm, however, activity limitations and participation restrictions are also clinically relevant. The authors have recently built a measure of an upper limb-impaired individual's ability to manage manual activities in daily life. Participation and quality of life are difficult outcomes to measure because they are multidimensional and depend on such factors as functional abilities, general physical health, financial security, and stability of the social and familial environment

A robust machine learning enabled decomposition of shear ground reaction forces during the double contact phase of walking.

Dynamic analyses of walking rely on the 3D ground reaction forces (GRF) under each foot, while only the resultant force of both limbs may be recorded on a single-belt instrumented treadmill or when both feet touch the same force platform. This study aims to develop a robust decomposition of the shear GRF to complete the most accurate decomposition of the vertical GRF [8]. A retrospective study of 374 healthy adults records (age: 22.8 ± 2.6 years, speed: 1.34 ± 0.28 m/s) and of 434 patient records (age: 21.3 ± 17.8 years, speed: 0.64 ± 0.19 m/s) were used in a machine learning process to develop a robust predictive model to decompose the fore-aft GRF. The lateral GRF was decomposed by resolving the equilibrium of transverse moments around the center of pressure. A predictive linear model of the fore-aft GRF under the back foot every 5% of the double contact phase was obtained from 2 predictors: the total fore-aft GRF and the vertical GRF under the back foot. Each predictor uses a time series of 31 samples before and during the double contact. The model performs accurately in healthy (median[IQR] error of 3.0[2.2-4.1]%) and in clinical gaits (7.7[4.7-13.4]%). The error in lateral GRF decomposition is of 5.7[3.9-10.2]% in healthy gaits and of 12.0[7.2-19.2]% in patients under the back foot and about half of that under the front foot. The decomposition of shear GRFs achieved in this study supports the mechanics of walking. It provides outstanding accuracy in healthy gait and also applies to neurologic and orthopedic disorders. Together with the vertical GRF decomposition [8], this approach for the shear components paves the way for robust single limb GRF determination on a single-belt instrumented treadmill or when both feet touch the same force platform in normal and clinical gait analysis