Block‐threshold‐adapted Estimators via a Maxiset Approach

We study the maxiset performance of a large collection of block thresholding wavelet estimators, namely the horizontal block thresholding family. We provide sufficient conditions on the choices of rates and threshold values to ensure that the involved adaptive estimators obtain large maxisets. Moreover, we prove that any estimator of such a family reconstructs the Besov balls with a near‐minimax optimal rate that can be faster than the one of any separable thresholding estimator. Then, we identify, in particular cases, the best estimator of such a family, that is, the one associated with the largest maxiset. As a particularity of this paper, we propose a refined approach that models method‐dependent threshold values. By a series of simulation studies, we confirm the good performance of the best estimator by comparing it with the other members of its family.     

Multichannels Strategy Implementation: The Role of Channel Alignment Capabilities*

A firm's distribution channels represent a key portfolio of resources that can be leveraged for competitive advantage. One approach to this portfolio that has become increasingly important in recent years is multichannel distribution (MCD). While this strategy has important benefits in terms of market coverage and firm performance, the use of multiple channels seriously affects downstream channel roles such as service delivery, as the financial rewards to channel members and the services they offer are separated. A channel member who offers poor or no service can free‐ride on the services offered to the same customer from a different channel. We draw on agency theory to explain these negative consequences. Additionally, the resource‐based view of the firm along with capabilities theory provides two key means of alleviating these consequences: channel tracking capabilities and reward alignment capabilities. The study, conducted in an industry facing serious MCD issues (the outdoor sporting goods industry), used key informant data matched to secondary data. Our results show that managers can reap the performance rewards of MCD strategies while minimizing its negative consequences. In particular, monitoring practices such as frequent site visits and phone contact with customers develop the firm's channel tracking capabilities, allowing managers to better monitor downstream activities. This becomes particularly important as the complexity from having multiple channels increases. Likewise, reward alignment capabilities such as retail price maintenance agreements and cooperative advertising enable the manager to minimize conflict among channel participants by ensuring sufficient profitability for all channel members.     

Generalized portmanteau statistics and tests of randomness

This paper considers the problem of testing the randomness of Gaussian and non–Gaussian time series. A general class of parametric portmanteau statistics, which include the Box–Pierce and the Ljung–Box statistics, is introduced. Using the exact first and second moments of the sample autocorrelations when the observations are i.i.d. normal with unknown mean, the exact expected value of any portmanteau statistics is obtained for this case. Two new portmanteau statistics, which exploit the exact moments of the sample autocorrelations, are studied. For the nonparametric case, a rank portmanteau statistic is introduced. The latter has the same distribution for any series of exchangeable random variables and uses the exact moments of the rank autocorrelations. We show that its asymptotic distribution is chi–squate. Simulation results indicate that the new portmanteau statistics are better approximated by the chi–square asymptotic distribution than the Ljung–Box statistics. Several analytical results presented in the paper were derived by usig a symbolic manipulation program.     

Measuring Substitution in Monetary-Asset Demand Systems

The Allen elasticity of substitution (AES) is widely used to study monetary-asset substitution and structural demand stability. Blackorby and Russell showed that the AES is uninformative and that the Morishima elasticity of substitution (MES) is the appropriate measure, a point overlooked in the monetary literature. Use of improper measures can lead to incorrect inferences. This article considers five alternative measures of substitution—the AES, the MES, the Hicksian and Marshallian elasticities of demand, and Mundlak's unencountered, but appealing, constant-cost elasticity of substitution. Selection of the substitution measure appropriate to respective research questions is addressed.     

MUST‐TAKE CARDS: MERCHANT DISCOUNTS AND AVOIDED COSTS

Antitrust authorities often argue that merchants cannot reasonably turn down payment cards and therefore must accept excessively high merchant discounts. The paper attempts to shed light on this must‐take cards view from two angles. First, the paper gives some operational content to the notion of must‐take card through the avoided‐cost test or tourist test: would the merchant want to refuse a card payment when a non‐repeat customer with enough cash in her pocket is about to pay at the cash register? It analyzes its relevance as an indicator of excessive interchange fees. Second, it identifies four key sources of potential social biases in the payment card systems' determination of interchange fees and compares the industry and social optima both in the short term (fixed number of issuers) and the long term (in which issuer offerings and entry respond to profitability).     

The effect of aging and tennis playing on coincidence-timing accuracy

This study examined the effect of tennis playing on the coincidence timing (CT) of older adults. Young, younger-old and older-old (20-30, 60-69, and 70-79 years old, respectively) tennis players and nonplayers were asked to synchronize a simple response (pressing a button) with the arrival of a moving stimulus at a target. Results showed that the older tennis players responded with a slight bias similar to that of the young players. Two experiments were conducted to determine whether the elimination of age effects through tennis playing was a result of maintaining basic perceptuomotor and perceptual processes or of some possible compensation strategy. The results revealed that the age-related increase in the visuomotor delay was significantly correlated with CT performance in older nonplayers but not in older tennis players. These results suggest that playing tennis is beneficial to older adults, insofar as they remained as accurate as younger ones despite less efficient perceptuomotor processes. This supports the compensation hypothesis.     

The central Europe experiment: Looking at persons and looking at objects

Gaze at objects, another person, and background was measured for fifteen dyads which constituted five different experimental groups in which task and situational factors were varied. The findings were that background stimuli had an unreliable effect on gaze; a very simple object relevant to the subject's task attracted a great deal of gaze and greatly reduced gaze at the other person. This effect was even stronger with a complex relevant object, where visual attention was almost completely transferred from the other person to the object. There was evidence of forces to avoid too much gaze at the other person. These findings suggested the possibility of postulating some new function of gaze in addition to information-seeking, or the possibility of an explanation in terms of the approach-avoidance model of gaze (Argyle & Dean, 1965).The authors are grateful to the S.S.R.C. for financial support.