Worker Speed Research Articles

The Speed of Earnings Responses to Taxation and the Role of Firm Labor Demand

This paper studies the speed at which workers' pre-tax earnings respond to tax changes along the intensive margin. We do so in the context of Germany, where a large discontinuity — or notch — in the tax schedule induces sharp bunching in the earnings distribution. We analyze earnings responses to two policy reforms that shift this notch outward. In a frictionless world, the workers that made up the excess mass at the old notch should all increase their earnings. While some of these workers indeed adjust their earnings rapidly, over 38% do not, and instead take several years to adjust. We propose that heterogeneity in firm labor demand plays a key role in generating the observed differences in the speed of workers' earnings responses and predict that adjustment will be quickest at growing firms. We test and find support for these demand-side effects in our linked employer-employee data.

The Speed of Earnings Responses to Taxation and the Role of Firm Labor Demand

This paper studies the speed at which workers' pre-tax earnings respond to tax changes along the intensive margin. We do so in the context of Germany, where a large discontinuity — or notch — in the tax schedule induces sharp bunching in the earnings distribution. We analyze earnings responses to two policy reforms that shift this notch outward. In a frictionless world, the workers that made up the excess mass at the old notch should all increase their earnings. While some of these workers indeed adjust their earnings rapidly, over 38% do not, and instead take several years to adjust. We propose that heterogeneity in firm labor demand plays a key role in generating the observed differences in the speed of workers' earnings responses and predict that adjustment will be quickest at growing firms. We test and find support for these demand-side effects in our linked employer-employee data.

Autocompletion interfaces make crowd workers slower, but their use promotes response diversity

Creative tasks such as ideation or question proposal are powerful applications of crowdsourcing, yet the quantity of workers available for addressing practical problems is often insufficient. To enable scalable crowdsourcing thus requires gaining all possible efficiency and information from available workers. One option for text-focused tasks is to allow assistive technology, such as an autocompletion user interface (AUI), to help workers input text responses. But support for the efficacy of AUIs is mixed. Here we designed and conducted a randomized experiment where workers were asked to provide short text responses to given questions. Our experimental goal was to determine if an AUI helps workers respond more quickly and with improved consistency by mitigating typos and misspellings. Surprisingly, we found that neither occurred: workers assigned to the AUI treatment were slower than those assigned to the non-AUI control and their responses were more diverse, not less, than those of the control. Both the lexical and semantic diversities of responses were higher, with the latter measured using word2vec. A crowdsourcer interested in worker speed may want to avoid using an AUI, but using an AUI to boost response diversity may be valuable to crowdsourcers interested in receiving as much novel information from workers as possible.

Autocompletion interfaces make crowd workers slower, but their use promotes response diversity

Creative tasks such as ideation or question proposal are powerful applications of crowdsourcing, yet the quantity of workers available for addressing practical problems is often insufficient. To enable scalable crowdsourcing thus requires gaining all possible efficiency and information from available workers. One option for text-focused tasks is to allow assistive technology, such as an autocompletion user interface (AUI), to help workers input text responses. But support for the efficacy of AUIs is mixed. Here we designed and conducted a randomized experiment where workers were asked to provide short text responses to given questions. Our experimental goal was to determine if an AUI helps workers respond more quickly and with improved consistency by mitigating typos and misspellings. Surprisingly, we found that neither occurred: workers assigned to the AUI treatment were slower than those assigned to the non-AUI control and their responses were more diverse, not less, than those of the control. Both the lexical and semantic diversities of responses were higher, with the latter measured using word2vec. A crowdsourcer interested in worker speed may want to avoid using an AUI, but using an AUI to boost response diversity may be valuable to crowdsourcers interested in receiving as much novel information from workers as possible.

Thermal adaptation and phosphorus shape thermal performance in an assemblage of rainforest ants.

We studied the Thermal Performance Curves (TPCs) of 87 species of rainforest ants and found support for both the Thermal Adaptation and Phosphorus-Tolerance hypotheses. TPCs relate a fitness proxy (here, worker speed) to environmental temperature. Thermal Adaptation posits that thermal generalists (ants with flatter, broader TPCs) are favored in the hotter, more variable tropical canopy compared to the cooler, less variable litter below. As predicted, species nesting in the forest canopy 1) had running speeds less sensitive to temperature; 2) ran over a greater range of temperatures; and 3) ran at lower maximum speeds. Tradeoffs between tolerance and maximum performance are often invoked for constraining the evolution of thermal generalists. There was no evidence that ant species traded off thermal tolerance for maximum speed, however. Phosphorus-Tolerance is a second mechanism for generating ectotherms able to tolerate thermal extremes. It posits that ants active at high temperatures invest in P-rich machinery to buffer their metabolism against thermal extremes. Phosphorus content in ant tissue varied three-fold, and as predicted, temperature sensitivity was lower and thermal range was higher in P-rich species. Combined, we show how the vertical distribution of hot and variable vs. cooler and stable microclimates in a single forest contribute to a diversity of TPCs and suggest that a widely varying P stoichiometry among these ants may drive some of these differences.

Mapping applications on volatile resource

In this paper, we study the execution of iterative applications on volatile processors such as those found on desktop grids. We envision two models, one where all tasks are assumed to be independent, and another where all tasks are tightly coupled and keep exchanging information throughout the iteration. These two models cover the two extreme points of the parallelization spectrum. We develop master–worker scheduling schemes that attempt to achieve good trade-offs between worker speed and worker availability. Any iteration entails the execution of a fixed number of independent tasks or of tightly coupled tasks. A key feature of our approach is that we consider a communication model where the bandwidth capacity of the master for sending application data to workers is limited. This limitation makes the scheduling problem more difficult both in a theoretical sense and in a practical sense. Furthermore, we consider that a processor can be in one of three states: available, down, or temporarily preempted by its owner. This preempted state also complicates the scheduling problem. In practical settings, for example desktop grids, master bandwidth is limited and processors are temporarily reclaimed. Consequently, addressing the aforementioned difficulties is necessary for successfully deploying master–worker applications on volatile platforms. Our first contribution is to determine the complexity of the scheduling problems in their offline versions, that is, when processor availability behaviors are known in advance. Even with this knowledge, the problems are NP-hard. Our second contribution is an evaluation of the expectation of the time needed by a worker to complete a set of tasks. We obtain a close formula for independent tasks and an analytical approximation for tightly coupled tasks. Those evaluations rely on a Markovian assumption for the temporal availability of processors, and are at the heart of some heuristics that aim at favoring ‘reliable’ processors in a sensible manner. Our third contribution is a set of heuristics for both models, which we evaluate in simulation. Our results provide guidance in selecting the best strategy as a function of processor state availability vs average task duration.

Microclimatic Conditions Regulate Surface Activity in Harvester Ants Messor barbarus

This paper analyses the effect of microclimatic factors (internal soil temperature, surface temperature and surface relative humidity) on surface activity of Messor barbarus harvester ants. We selected 44 colonies in an area of Mediterranean grassland near Madrid (Central Spain), which were monitored for activity between March 1998 and September 1999. Results indicate that microclimatic factors are good predictors of colony activation and intensity of activity. Colonies became active above certain critical values of internal soil temperature and relative humidity. For active colonies, surface temperature was the main regulatory factor for worker departure rate, which peaked at around 25–30°C. Worker speed was positively correlated with surface temperature, although the relationship was weaker for large-sized workers. Microclimatic factors were not enough, however, to predict task allocation outside the nest. The explanation for this aspect of ant behavior probably requires the inclusion of biotic factors in the models.

Behaviour of army antsEciton burchelli andE. hamatum (Hymenoptera, Formicidae) in the Belem region III. Raid activity

A study on the raiding behaviour ofE. burchelli (Westwood) andE. hamatum (Fabricius) was carried out in an Amazonian forest reserve at Instituto de Pesquisa e Experimentacao Agropecuarias do Norte (IPEAN), Belem, State of Para, Brazil. The data were collected during the years 1966 and 1968, on 5E. burchelli and 1E. hamatum colonies, with emphasis on the quantitative aspects (raid trail length, frequency and duration of raid activity, speed of workers on base column, booty types, and direction of raid trail). The average trail length was 75.4±3.3 m forE. burchelli, as calculated from 306 raid trails recorded during 24 nomadic phases; the figures forE. hamatum were 195±13.4 m, 54 and 5 respectively. A significant difference (0.01<P<0.05) was observed between the nomadic and statary phase, both forE. burchelli (308 records) andE. hamatum (72 records), with respect to raid trail length. The nomadic raids of both species are longer than those of the statary phase. The season of the year had a significant influence on raid trail length, but no relationship was found between raid trail length and the days of nomadic or statary phase. Data on worker speed on the raid trails, booty types and direction of the raid are also presented.

Effects of Worker Speed in Carding

Effects of Worker Speed in Carding