Showing papers by "Tilburg University published in 1989"

Distance-Regular Graphs

Abstract: Consider a connected simple graph with vertex set X of diameter d. Define Ri X2 by (x, y) Ri whenever x and y have graph distance

The contribution of general features of body movement to the attribution of emotions

Abstract: The present study was designed to assess the contribution of general features of gross body movements to the attribution of emotions. Eighty-five adult subjects were shown ninety-six videotaped body movements, performed by three actors. Each movement was determined by seven general dimensions: trunk movement, arm movement, vertical direction, sagittal direction, force, velocity and directness. Using rating scales, the subjects judged the compatibility of each movement with each of twelve emotion categories. The results showed which movement features predicted particular ratings. Emotion categories differed as to the amount, type, and weights of predicting movement features. Three factors were extracted from the original ratings and interpreted as Rejection-Acceptance, Withdrawal-Approach, and Preparation-Defeatedness.

Equivalence of Cross-Cultural Data: An Overview of Basic Issues

Abstract: The logic of comparison is taken as a starting point. It is argued that any cross-cultural comparison presupposes a comparison scale, i.e. a scale that is identical across the populations included in a study. Scale identity can be Specified for various levels of measurement. In the second section a simple classification is presented for inferences about cross-cultural differences derived from psychological measurements. Two questions are asked for various categories of inferences, viz., whether they are logically feasible and whether they can be validated empirically. In the third section the statistical analysis of psychometric conditions for equivalence is discussed. The fourth section deals with the problem what alternatives for meaningful interpretation a researcher has if data turn out to be lacking in equivalence. In the fifth section a conceptual problem is raised. namely whether the basic assumption of this article is realistic that psychological concepts are identical across cultures.

On the size of systems of sets every t of which have an SDR, with an application to the worst-case ratio of heuristics for packing problems

Abstract: Let $E_1 ,\cdots,E_m $ be subsets of a set V of size n, such that each element of V is in at most k of the $E_i $ and such that each collection of t sets from $E_1 ,\cdots ,E_m $ has a system of distinct representatives (SDR). It is shown that $m/n\leqq (k(k - 1)^r - k)/(2(k - 1)^r - k)$ if $t = 2r - 1$, and $m/n \leqq (k(k - 1)^r - 2)/(2(k - 1)^r - 2)$ if $t = 2r$. Moreover it is shown that these upper bounds are the best possible. From these results the “worst-case ratio” of certain heuristics for the problem of finding a maximum collection of pairwise disjoint sets among a given collection of sets of size k is derived.

Workloads and waiting times in single-server systems with multiple customer classes

Abstract: One of the most fundamental properties that single-server multi-class service systems may possess is the property of work conservation. Under certain restrictions, the work conservation property gives rise to a conservation law for mean waiting times, i.e., a linear relation between the mean waiting times of the various classes of customers. This paper is devoted to single-server multi-class service systems in which work conservation is violated in the sense that the server's activities may be interrupted although work is still present. For a large class of such systems with interruptions, a decomposition of the amount of work into two independent components is obtained; one of these components is the amount of work in the corresponding systemwithout interruptions. The work decomposition gives rise to a (pseudo)conservation law for mean waiting times, just as work conservation did for the system without interruptions.

Workloads and waiting times in single-server systems with multiple customer classes

Abstract: One of the most fundamental properties that single-server multi-class service systems may possess is the property of work conservation. Under certain restrictions, the work conservation property gives rise to a conservation law for mean waiting times, i.e., a linear relation between the mean waiting times of the various classes of customers. This paper is devoted to single-server multi-class service systems in which work conservation is violated in the sense that the server's activities may be interrupted although work is still present. For a large class of such systems with interruptions, a decomposition of the amount of work into two independent components is obtained; one of these components is the amount of work in the corresponding systemwithout interruptions. The work decomposition gives rise to a (pseudo)conservation law for mean waiting times, just as work conservation did for the system without interruptions.

Analysis and computation of (n,N) : Strategies for maintenance of a two-component system

Abstract: In this paper ( n , N )-strategies are investigated for the maintenance of a two component series system. Vergin and Scriabin [8] provided some numerical evidence on the near-optimality of this type of policies. In a recent paper, Ozekici [5] gave a characterization of the structure of the optimal policy and its possible deviations from the ( n , N )-structure for the discounted cost criterion. The same kind of structure is shown to hold for the average cost criterion. In view of the complicated form of the optimal policy and the near-optimality of the ( n , N )-policies we present a fast computational method to compute the average costs under a given ( n , N )-policy. This method is based on a well-known embedding technique. Moreover, a heuristic based on this computational method, is presented by which the optimal values of n and N can be determined.

Latent Class Models for the Analysis of Rankings

Abstract: In this papers several latent class models for the analysis of rank order data are developed and discussed. These models try to accommodate the rationale of individual choice models to the situation in which a large number of respondents is sampled from a non-homogeneous population. By considering these individual choice models as statistical error theories, these models may be seen to fall within the domain of general latent structure analysis and as such, they may provide a viable alternative to the more traditional scaling methods for the analysis of rankings.

Brand Confusion in Advertising

Abstract: The question of advertising effectiveness (i.e., to what extent is advertising effective or ineffective?) is possibly the most important question asked of or by advertisers. In this article, the authors provide evidence that advertising may also be counter-effective, that is, produce results that an advertiser specifically wants to avoid. Brand confusion is one such undesired result: the advertisement for brand A is taken by consumers as promoting brand B. In other words, the advertiser finances an advertisement for his competitor. In the second part of the article, several possible causes of brand confusion are presented, and practical advertising implications are discussed.

Power Approximations to Multinomial Tests of Fit

Abstract: Multinomial tests for the fit of iid observations X 1 …, Xn to a specified distribution F are based on the counts Ni of observations falling in k cells E 1, …, Ek that partition the range of the X j . The earliest such test is based on the Pearson (1900) chi-squared statistic: X 2 = Σ k i=1 (Ni – npi )2/npi , where pi = PF (Xj in Ei ) are the cell probabilities under the null hypothesis. A common competing test is the likelihood ratio test based on LR = 2 Σ k i=1 Ni log(Ni/npi ). Cressie and Read (1984) introduced a class of multinomial goodness-of-fit statistics, R λ, based on measures of the divergence between discrete distributions. This class includes both X 2 (when λ = 1) and LR (when λ = 0). All of the R λ have the same chi-squared limiting null distribution. The power of the commonly used members of the class is usually approximated from a noncentral chi-squared distribution that is also the same for all λ. We propose new approximations to the power that vary with the statistic chosen. Bot...

A Pseudoconservation Law for Service Systems with a Polling Table.

Abstract: The analysis of waiting times in polling systems in which the stations are polled according to a general service-order table is discussed. Such systems can be used to represent token-bus local area networks in which the routing of the token is fixed. Stations are given higher priority by being listed more frequently in the table, or by receiving service according to the exhaustive service discipline. The polling system is modeled by a single-server multiqueue system in discrete time. Nonzero switchover times between the queues are assumed. An extension of the principle of work conservation to systems with nonzero switchover times leads to an exact expression for a weighted sum of the mean waiting times at the various queues. By using a limiting procedure, the discrete-time results are translated to continuous-time results. The special case of polling in a star network is discussed and compared to polling in a corresponding network with strictly cyclic service order. >

RIDL*: a tool for the computer-assisted engineering of large databases in the presence of integrity constraints

Abstract: Tools and methods that transform higher level formalisms into logical database designs become very important. Rarely if ever do these transformations take into account integrity constraints existing in the “conceptual” model. Yet these become essential if one is forced to introduce redundancies for reasons of e.g. query efficiency. We therefore adopted the Binary Relationship Model (or “NIAM”) that is rich in constraints and built a flexible tool, RIDL*, that graphically captures NIAM semantic networks, analyzes them and then transforms them into relational designs (normalized or not), under the control of a database engineer assisted by a rule base. This is made possible by a rule-driven implementation of a new, stepwise synthesis process, and its benefits are illustrated by its treatment of e.g. subtypes. RIDL* is operational at several industrial sites in Europe and the U.S. on sizeable database projects.

Intragenerational stability of postmaterialism in Germany, the Netherlands and the United States

Abstract: Inglehart's thesis of the 'Silent Revolution' states that the priorities of Western publics have gradually shifted from materialist toward postmaterialist values. An important aspect of this thesis is the socialization hypothesis, predicting that one's (post)-materialist values are stable during adulthood. This paper tests this hypothesis using panel data for the United States, Germany and the Netherlands. For this purpose several multiple indicator two-wave models are developed including (i) a correction for the dependency between the indicators (because of the ranking of the items) and (ii) item specific factors. Application of these models to the data indicates a strong stability of postmaterialist values during adulthood, especially for the United States and the Netherlands. The implications of the findings are discussed.

A relational formulation of the theory of types

Abstract: This paper developes a relational---as opposed to a functional---theory of types. The theory is based on Hilbert and Bernays' eta operator plus the identity symbol, from which Church's lambda and the other usual operators are then defined. The logic is intended for use in the semantics of natural language.

A Simplicial Algorithm for Stationary Point Problems on Polytopes

Abstract: A simplicial variable dimension restart algorithm for the stationary point problem or variational inequality problem on a polytope is proposed. Given a polytope C in Rn and a continuous function f: C → Rn, find a point x in C such that fx · x ≥ fx · x for any point x in C. Starting from an arbitrary point v in C, the algorithm generates a piecewise linear path of points in C. This path is followed by alternating linear programming pivot steps to follow a linear piece of the path and replacement steps in a simplicial subdivision of C. Within a finite number of function evaluations and linear programming pivot steps the algorithm finds an approximate stationary point. The algorithm leaves the starting point v along a ray pointing to one of the vertices w of C. The vertex w is obtained from the optimum solution of the linear programming problem maximize fv · x subject to x ∈ C.

Savings And Costs Of A Picture Archiving And Communication System In The University Hospital Utrecht

Abstract: The evaluation of the Dutch PACS project comprises amongst other studies a comparison of the direct financial costs of the present conventional system and the PACSystem. This paper shows that the invest-ment costs of a PACSystem are presently substantially higher than of the present system. These higher investment costs will not be compensated for by savings in the area of materials used, floor space needed, and personnel employed. The only cost effective compensation can be found in a shortening of the length of patient stay in the hospital. Preliminary results of the ongoing experiment suggest that compensation is achieved by an average decrease of one third day. Conditions under which a PACSystem can be more cost effective are being discussed.

Macroeconomic policy games with incomplete information : Some extensions

Abstract: Publisher Summary This chapter discusses a few extensions of macroeconomic policy games with incomplete information It presents generalizations of simple models of macroeconomic policy with incomplete information, with the purpose of finding out how sensitive their implications are to changes in assumptions The basic result of the simple analysis is that the reputation effect can constrain a government to mimic the behavior of a government that is committed to a zero-inflation strategy, so long as the government has a sufficiently long time-horizon or a sufficiently long period of time remaining in office The chapter explores a two-period game and the simple change to the model made by adding uncertainty about the effects of policy complicates the analysis considerably The reputational constraints on macroeconomic policy remain effective when the private sector's beliefs about possible government types are generalized, but imperfect monitoring of government actions weakens those constraints considerably

Monitoring in children's second language speech:

Abstract: The present study investigates the monitoring behaviour of Turkish children speaking Dutch as a second language. Spontaneous speech data were collected over a period of two years at one-year intervals with 74 children from the time they entered Dutch primary schools. In order to discover developmental changes, a typology of monitoring behaviour was given as a function of the children's age. A distinction was made between corrections, restarts and repeats. With regard to corrections, phonological, syntactic and semantic types were distinguished. In order to explain the individual variation in monitoring, the occurrence of monitoring types was correlated with nonverbal cognitive skill and with oral second language proficiency. The structure of monitoring processes was investigated by determining the point in the utterance at which children go back to make a new start for correction, after they have detected an error. The results show that during the process of second language acquisition different types of ...

Simultaneous Models for Migration and Commuting: Macro and Micro Economic Approaches

Abstract: Spatial labour markets are generally characterized by a demand for specific skills that does not automatically match the supply of persons having such capabilities. Demand and supply are brought closer together by spatial mobility of workers. It can be argued that the evolution of industrialized societies into societies of specialized education and labour demand, requires a mobility policy designed to avoid a growth in discrepancies in spatial labour markets. Since both people and jobs become increasingly heterogeneous according to skills, qualifications and locational preferences spatial mobility can be one of the necessary lubricants for the labour market and, hence, may at least partly solve the matching problem.