Monetary Incentives in Mail Surveys

Eighteen empirical studies from fourteen different researchers provide evidence that prepaid monetary incentives have a strong positive impact on the response rate in mail surveys. One of these studies is described here and an attempt is made to generalize from all eighteen about the relationship between size of incentives and reduction in nonresponse. These generalizations should be of value for the design of mail survey studies

Strategies for Implementing Change: An Experiential Approach

An attitude survey and a role-playing case were used to identify the typical approaches people use to implement important changes in organizations. This typical strategy, suggested or used by over 90% of the subjects, was not successful in producing change in any of the fourteen role-playing trials. However, with ten minutes of instruction in the ”Delta Technique,” 86% of the subjects were successful in introducing change in another fourteen role-playing trials. The ”Delta Technique” consists of simple rules drawn from half a century of research

Forecasting with Econometric Methods: Folklore versus Fact

Evidence from social psychology suggests that econometricians will avoid evidence that disconfirms their beliefs. Two beliefs of econometricians were examined: (1) Econometric methods provide more accurate short-term forecasts than do other methods; and (2) more complex econometric methods yield more accurate forecasts. A survey of 21 experts in econometrics found that 95% agreed with the first statement and 72% agreed with the second. A review of the published empirical evidence yielded little support for either of the two statements in the 41 studies. The method of multiple hypotheses was suggested as a research strategy that will lead to more effective use of disconfirming evidence. Although this strategy was suggested in 1890, it has only recently been used by econometricians

Cheating in Management Science (with Comments by M. K. Starr and M. J. Mahoney)

Honesty is vital to scientific work and, clearly, most scientists are honest. However, recent publicity about cases involving cheating, including cases of falsification of data and plagiarism, raises some questions: Is cheating a problem? Does it affect management science? Should anything be done

Learner Responsibility in Management Education, or Ventures into Forbidden Research (with Comments)

Formal education can be improved by transferring responsibility from the teacher to the learner. A simple approach to this is the time contract. Time contracts have been used successfully in nine quasi-experiments but, despite these successes, some educators see this as subversive research

Estimating Nonresponse Bias in Mail Surveys

Valid predictions for the direction of nonresponse bias were obtained from subjective estimates and extrapolations in an analysis of mail survey data from published studies. For estimates of the magnitude of bias, the use of extrapolations led to substantial improvements over a strategy of not using extrapolations

Two sided markets, competitive bottlenecks and exclusive contracts

We provide a framework for analyzing two-sided markets that allows for different degrees of product differentiation on each side of the market. When platforms are viewed as homogenous by sellers but heterogeneous by buyers, we show that “competitive bottlenecks” arise endogenously. In equilibrium, platforms do not compete directly for sellers, instead choosing to compete indirectly by subsidizing buyers to join. Sellers are left with none of the gains from trade. Despite this, it is sellers who choose to purchase from multiple platforms (multihome). Finally, the role of exclusive contracts to prevent multihoming is explored

Studies of intercellular invasion in vitro using rabbit peritoneal neutrophil granulocytes (PMNS). I. Role of contact inhibition of locomotion.

Intercellular invasion is the active migration of cells on one type into the interiors of tissues composed of cells of dissimilar cell types. Contact paralysis of locomotion is the cessation of forward extension of the pseudopods of a cell as a result of its collision with another cell. One hypothesis to account for intercellular invasion proposes that a necessary condition for a cell type to be invasive to a given host tissue is that it lack contact paralysis of locomotion during collision with cells of that host tissue. The hypothesis has been tested using rabbit peritoneal neutrophil granulocytes (PMNs) as the invasive cell type and chick embryo fibroblasts as the host tissue. In organ culture, PMNs rapidly invade aggregates of fibroblasts. The behavior of the pseudopods of PMNs during collision with fibroblasts was analyzed for contact paralysis by a study of time-lapse films of cells in mixed monolayer culture. In monolayer culture, PMNs show little sign of paralysis of the pseudopods upon collision with fibroblasts and thus conform in their behavior to that predicted by the hypothesis

The Case for Minimum Teaching Standards

We all share the desire to improve the learning environment at Wharton and to have students who will be satisfied with this environment. While most of the Wharton Teaching Committee's recommendations are consistent with these aims, I believe that recommendation #1, to 'Establish Minimum Standards for Acceptable Teaching,'' will be detrimental to learning. I therefore recommend that we reject proposal #1. This letter describes how I reached this conclusion, suggests alternatives, and recommends a process for resolving tie issues.learning, universities, business schools

Damped Seasonality Factors: Introduction

Previous research has shown that seasonal factors provide one of the most important ways to improve forecast accuracy. For example, in forecasts over an 18-month horizon for 68 monthly economic series from the M-Competition, Makridakis et al. (1984, Table 14) found that seasonal adjustments reduced the MAPE from 23.0 to 17.7 percent, an error reduction of 23%. On the other hand, research has also shown that seasonal factors sometimes increase forecast errors (e.g., Nelson, 1972). So, when forecasting with a data series measured in intervals that represent part of a year, should one use seasonal factors or not? Statistical tests have been devised to answer this question, and they have been quite useful. However, some people might say that the question is not fair. Why does it have to be either/or? Shouldn^Rt the question be ^Sto what extent should seasonal factors be used for a given series?^Tseasonal factors, forecast, accuracy