Social Workers as Entrepreneurs

Qualified social workers were employed in the newly established Community Service Centers (Matnas) in Israel to take part in efforts to initiate services and define each Matnas' domain. The organizational structure of a Matnas encourages its workers to use their professional skills in making entrepreneurial initiatives: The local board, the untenured, multidisciplinary staff, and the ability to utilize mixed resources, affords the Matnas the flexibility to easily contract ‘in’ and ‘out’ of programs, giving it and its staff a competitive position within the free market of service providers. This structure also permits the establishment of formal and informal contacts with constituents and authorities. This paper presents the case and discusses the role of social workers in innovating service programs.     

On competing rewards standards—an experimental study of ultimatum bargaining

In the tradition of earlier experimental studies, this paper introduces competing reward standards by letting parties bargain over the distribution of chips. The monetary equivalents of a chip for the bargaining parties can be equal (no competing rewards) or different (competing rewards). The ultimatum game is used as a tool to learn about reward standards in an asymmetric procedure. A major effect of different monetary chip equivalents is observed only when the proposer has a higher chip value. Results are compared to those reported in [Games Econ. Behav. 13 (1966) 100], who used a different experimental design.     

Local search algorithms for multiple-depot vehicle routing and for multiple traveling salesman problems with proved performance guarantees

We consider two related problems: the multiple-depot vehicle routing problem (MDVRP) and the Multiple traveling salesman problem (mTSP). In both of them, given is the complete graph on n vertices \(G = (V,E)\) with nonnegative edge lengths that form a metric on V. Also given is a positive integer k. In typical applications, V represents locations of customers and k represents the number of available vehicles. In MDVPR, we are also given a set of k depots \(\{O_1,\ldots ,O_k\} \subseteq V\) , and the goal is to find a minimum-length cycle cover of G of size k, that is, a collection of k (possibly empty) cycles such that each \(v \in V\) is in exactly one cycle, and each cycle in the cover contains exactly one depot. In mTSP, no depots are given, so the goal is to find (any) minimum-length cycle cover of G of size k. We present local search algorithms for both problems, and we prove that their approximation ratio is 2.     

ON THE RELATIVE EFFICIENCY OF PERFORMANCE PAY AND NONCONTINGENT INCENTIVES

We report evidence from a large field experiment that compares the effectiveness of contingent and noncontingent incentives in eliciting costly effort for a large range of payment levels. The company with which we worked sent 7,250 letters asking customers to complete a survey. Some letters promised to pay amounts ranging from $1 to $30 upon compliance (contingent incentives), whereas others already contained the money in the request envelopes (noncontingent incentives). Compared to no payment, very small contingent payments lower the response rate while small noncontingent payments raise the response rate. As expected, response rates rise with the size of the incentive offered. The response rate in the noncontingent incentives rises more rapidly for low amounts of incentive, but then flattens out and reaches lower levels than under contingent payments. We discuss how the optimal policy regarding the use of each size and type of incentives crucially depends on firms’ objectives.     

Gender Differences in Competition: Evidence From a Matrilineal and a Patriarchal Society

We use a controlled experiment to explore whether there are gender differences in selecting into competitive environments across two distinct societies: the Maasai in Tanzania and the Khasi in India. One unique aspect of these societies is that the Maasai represent a textbook example of a patriarchal society, whereas the Khasi are matrilineal. Similar to the extant evidence drawn from experiments executed in Western cultures, Maasai men opt to compete at roughly twice the rate as Maasai women. Interestingly, this result is reversed among the Khasi, where women choose the competitive environment more often than Khasi men, and even choose to compete weakly more often than Maasai men. These results provide insights into the underpinnings of the factors hypothesized to be determinants of the observed gender differences in selecting into competitive environments.     

The Black Gender Gap in Educational Attainment: Historical Trends and Racial Comparisons

It is often asserted that the gender gap in educational attainment is larger for blacks than whites, but historical trends comparing the black and white gender gap have received surprisingly little attention. Analysis of historical data from the U.S. census IPUMS samples shows that the gender gap in college completion has evolved differently for whites and blacks. Historically, the female advantage in educational attainment among blacks is linked to more favorable labor market opportunities and stronger incentives for employment for educated black women. Blacks, particularly black males, still lag far behind whites in their rates of college completion, but the striking educational gains of white women have caused the racial patterns of gender differences in college completion rates to grow more similar over time. While some have linked the disadvantaged position of black males to their high risk of incarceration, our estimates suggest that incarceration has a relatively small impact on the black gender gap and the racial gap in college completion rates for males in the United States.     

The Structure of Technology in a Multioutput Branch Banking Firm

We formulate and estimate a multioutput bank's cost function amenable for distinguishing between economies of scale and economies of network density. We find significant returns to network density, especially for smaller banks. Diseconomies of scale are found for the larger banks, whereas the hypothesis of constant returns to scale could not be rejected for the smaller banks.     

Number of matches and matched people in the birthday problem

The well known birthday problem asks for the probability of at least one match out of a group of n people. Also of interest are the number of matches and the number of matched people. In this paper the means and variances of the number of matches and matched people are obtained. A generalization of the use of these methods to computer storage analysis is discussed.     

CONTINUOUS-TIME FILTERS FOR STATE ESTIMATION FROM POINT PROCESS MODELS OF NEURAL DATA

Neural spike trains, the primary communication signals in the brain, can be accurately modeled as point processes. For many years, significant theoretical work has been done on the construction of exact and approximate filters for state estimation from point process observations in continuous-time. We have previously developed approximate filters for state estimation from point process observations in discrete-time and applied them in the study of neural systems. Here, we present a coherent framework for deriving continuous-time filters from their discrete-counterparts. We present an accessible derivation of the well-known unnormalized conditional density equation for state evolution, construct a new continuous-time filter based on a Gaussian approximation, and propose a method for assessing the validity of the approximation following an approach by Brockett and Clark. We apply these methods to the problem of reconstructing arm reaching movements from simulated neural spiking activity from the primary motor cortex. This work makes explicit the connections between adaptive point process filters for analyzing neural spiking activity in continuous-time, and standard continuous-time filters for state estimation from continuous and point process observations.