Gift Exchange within a Firm: Evidence from a Field Experiment

We present results from a field experiment testing the gift-exchange hypothesis inside a tree-planting firm paying its workforce incentive contracts. Firm managers told a crew of tree planters they would receive a pay raise for one day as a result of a surplus not attribuable to past planting productivity. We compare planter productivity - the number of trees planted per day - on the day the gift was handed out with productivity on previous and subsequent days of planting on the same block, and thus under similar planting conditions. We find direct evidence that the gift had a significant and positive effect on daily planter productivity, controlling for planter-fixed effects, weather conditions and other random daily shocks. Moreover, reciprocity is the strongest when the relationship between planters and the firm is long term.Subsidy, Marginal Tax Reforms, Egypt

On the Relevance and Composition of Gifts within the Firm: Evidence from Field Experiments

We investigate the economic relevance and the composition of gifts within a firm where output is contractible. We develop a structural econometric model that identifies workers’ optimal reaction to monetary gifts received from their employer. We estimate the model using data from two separate field experiments, both conducted within a tree-planting firm. We use the estimated structural parameters to generalize beyond the experiment, simulating how workers would react to different gifts on the part of the firm, within different labour-market settings. We find that gifts have a role to play within this firm, increasing in importance when the workers’ outside alternatives deteriorate. Profit-maximizing gifts would increase profits within slack labour markets by up to 10% on average and by up to 17% for certain types of workers. These gifts represent significant increases in worker earnings; the average gift paid to workers attains 22% of average expected earnings in the absence of gifts. We find that gifts should be given by setting piece-rates above the market-clearing level rather than through fixed wages.Gift giving, structural models, field experiments

On the Relevance and Composition of Gifts within the Firm: Evidence from Field Experiments

We investigate the economic relevance and the composition of gifts within a firm where output is contractible. We develop a structural econometric model that identifies workers' optimal reaction to monetary gifts received from their employer. We estimate the model using data from two separate field experiments, both conducted within a tree-planting firm. We use the estimated structural parameters to generalize beyond the experiment, simulating how workers would react to different gifts on the part of the firm, within different labour-market settings. We find that gifts have a role to play within this firm, increasing in importance when the workers' outside alternatives deteriorate. Profit-maximizing gifts would increase profits within slack labour markets by up to 10% on average and by up to 17% for certain types of workers. These gifts represent significant increases in worker earnings; the average gift paid to workers attains 22% of average expected earnings in the absence of gifts. We find that gifts should be given by setting piece-rates above the market-clearing level rather than through fixed wages.gift giving, structural models, field experiments

Sorting, Incentives and Risk Preferences: Evidence from a Field Experiment

The, often observed, positive correlation between incentive intensity and risk has been explained in two ways: the presence of transaction costs as determinants of contracts and the sorting of risk-tolerant individuals into firms using high-intensity incentive contracts. The empirical importance of sorting is perhaps best evaluated by directly measuring the risk tolerance of workers who have selected into incentive contracts under risky environments. We use experiments, conducted within a real firm, to measure the risk preferences of a sample of workers who are paid incentive contracts and face substantial daily income risk. Our experimental results indicate the presence of sorting; Workers in our sample are risk-tolerant. Moreover, their level of tolerance is considerably higher than levels observed for samples of individuals representing broader populations. Interestingly, the high level of risk tolerance suggests that both sorting and transaction costs are important determinants of contract choices when workers have heterogeneous preferences.Risk aversion, sorting, incentive contracts, field experiments

Peer Pressure, Incentives, and Gender: an Experimental Analysis of Motivation in the Workplace

We present results from a real-effort experiment, simulating actual work-place conditions, comparing the productivity of workers under fixed wages and piece rates. Workers, who were paid to enter data, were exposed to different degrees of peer pressure under both payment systems. The peer pressure was generated in the form of private information about the productivity of their peers. We have two main results. First, we find no level of peer pressure for which the productivity of either male or female workers is significantly higher than productivity without peer pressure. Second, we find that very low and very high levels of peer pressure can significantly decrease productivity (particularly for men paid fixed wages). These results are consistent with models of conformism and self-motivation.Peer effects, fixed wages, piece rates, gender

Gift Exchange within a Firm: Evidence from a Field Experiment

We present results from a field experiment testing the gift-exchange hypothesis inside a tree-planting firm paying its workforce incentive contracts. Firm managers told a crew of tree planters they would receive a pay raise for one day as a result of a surplus not attributable to past planting productivity. We compare planter productivity - the number of trees planted per day - on the day the gift was handed out with productivity on previous and subsequent days of planting on the same block, and thus under similar planting conditions. We find direct evidence that the gift had a significant and positive effect on daily planter productivity, controlling for planter-fixed effects, weather conditions and other random daily shocks. Moreover, reciprocity is the strongest when the relationship between planters and the firm is long term

Assumptions, trust, and names in computer security protocols

A major goal of using any security protocol is to create certain beliefs in the participants. A security protocol will use techniques like cryptography to guarantee some things, but it will still require a participant to make assumptions about other things that the protocol cannot guarantee; such assumptions often constitute trust in other participants. In this thesis, we attempt to precisely identify the required assumptions of some example protocols. In the process, we find that we must consider the names that participants use to reason about each other. It turns out that naming is a complex topic with a rich body of philosophical work, and we apply some ideas from this work to the problem of identifying security protocols' required assumptions. Finally, we begin work on a mathematical model of protocols and beliefs to which a formal logic of belief could be applied. The model is left incomplete because of some unresolved problems with modeling belief caused by the design requirement that the model's elements have clear operational meanings. The solution of these problems is left as future work.http://archive.org/details/assumptionstrust109455657Approved for public release; distribution is unlimited

Werdingite from the Urungwe District, Zimbabwe

Electron and ion microprobe data on two samples of welshite from the type locality of Langban, Sweden, gave analytical totals of 99.38-99.57 wt.% and BeO contents of 4.82-5.11 wt.%, corresponding to 1.692-1.773 Be/20 O. Mossbauer and optical spectra of o

Insights into the Mechanism of Intermediate-Depth Earthquakes from Source Properties as Imaged by Back Projection of Multiple Seismic Phases

This study investigates the spatial and temporal distribution of energy release of large, intermediate-depth earthquakes using a modified back projection technique first used to study the 2004 Sumatra-Andaman megathrust event. Multiple seismic phases are included in the back projection analysis, which provides the capability to determine the energy distribution with respect to depth and time. A total of 22 intermediate-depth earthquakes with moment magnitudes greater than or equal to 6.5 are investigated with hypocentral depths between 100 and 300 km. For most of these events, the vertical extent of energy release is either below the resolution of this study $(\leq5 km)$ or slightly above $(\leq15 km)$. This observation agrees with previous studies that find large, intermediate-depth earthquakes have subhorizontal rupture planes. The results also show a significant portion of the events have multiple rupture planes that are well separated in depth. The closeness in time of the ruptures on separate planes and the distance between the planes suggest dynamic triggering where the P waves from the first rupture initiate rupture on the second plane. We propose that a dehydration embrittlement mechanism combined with preferentially hydrated subhorizontal faults can explain the observations of dominant subhorizontal rupture planes and the frequent occurrence of rupture complexity involving multiple subevents.Earth and Planetary Science