scholarly journals The Use of Field Experiments to Study Mechanisms of Discrimination

2016 ◽  
Vol 38 (1) ◽  
Author(s):  
Marc Keuschnigg ◽  
Tobias Wolbring
Keyword(s):  
Observational Data ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Lessons Learned ◽  
Statistical Discrimination ◽  
Differential Treatment ◽  
Experimental Designs ◽  
Social Mechanisms ◽  
Causal Pathways ◽  
Approaches To Study

AbstractThis paper discusses social mechanisms of discrimination and reviews existing field experimental designs for their identification. We first explicate two social mechanisms proposed in the literature, animus-driven and statistical discrimination, to explain differential treatment based on ascriptive characteristics. We then present common approaches to study discrimination based on observational data and laboratory experiments, discuss their strengths and weaknesses, and elaborate why unobtrusive field experiments are a promising complement. However, apart from specific methodological challenges, well-established experimental designs fail to identify the mechanisms of discrimination. Consequently, we introduce a rapidly growing strand of research which actively intervenes in market activities varying costs and information for potential perpetrators to identify causal pathways of discrimination. We end with a summary of lessons learned and a discussion of challenges that lie ahead.

scholarly journals Breaking Empirical Deadlocks in the Study of Partisanship: An Overview of Experimental Research Strategies

2013 ◽  
Vol 1 (1) ◽  
pp. 6-15 ◽  
Author(s):  
Donald P. Green
Keyword(s):  
Observational Data ◽  
Experimental Research ◽  
Field Experiments ◽  
Party Identification ◽  
Experimental Designs ◽  
Performance Evaluations ◽  
Research Strategies ◽  
Short Term ◽  
Vast Literature ◽  
Shed Light

The vast literature on party identification has gradually become bogged down by disputes about how to interpret observational data. This paper proposes the use of experimental designs to shed light on the responsiveness of party identification to short term forces such as retrospective performance evaluations. Examples of recent field experiments are used to illustrate two types of experimental designs and the assumptions on which they rest.

Concentration of Impurities during Melting of Snow Made from Secondary Sewage Effluent

1986 ◽  
Vol 18 (2) ◽  
pp. 151-156 ◽  
Author(s):  
R. Zapf-Gilje ◽  
S. O. Russell ◽  
D. S. Mavinic
Keyword(s):  
Potassium Chloride ◽  
Chloride Solution ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Low Cost ◽  
Sewage Effluent ◽  
Potassium Chloride Solution ◽  
Laboratory Results ◽  
Solution Field ◽  
Concentration Of Impurities

When snow is made from sewage effluent, the impurities become concentrated in the early melt leaving the later runoff relatively pure. This could provide a low cost method of separating nutrients from secondary sewage effluent. Laboratory experiments showed that the degree of concentration was largely independent of the number of melt freeze cycles or initial concentration of impurity in the snow. The first 20% of melt removed with it 65% of the phosphorus and 90% of the nitrogen from snow made from sewage effluent; and over 90% of potassium chloride from snow made from potassium chloride solution. Field experiments with a salt solution confirmed the laboratory results.

scholarly journals Interactions Between Chill-Hours and Degree-Days Affect Carpogenic Germination in Monilinia vaccinii-corymbosi

2001 ◽  
Vol 91 (1) ◽  
pp. 77-83 ◽  
Author(s):  
H. Scherm ◽  
A. T. Savelle ◽  
P. L. Pusey
Keyword(s):  
Laboratory Experiments ◽  
Field Experiments ◽  
Degree Days ◽  
Carpogenic Germination ◽  
Conditioning Period ◽  
Low Degree ◽  
Heating Degree Days ◽  
Relationship Of ◽  
High Degree ◽  
The Relationship

The relationship of cumulative chill-hours (hours with a mean temperature <7.2°C) and heating degree-days (base 7.2°C) to carpogenic germination of pseudosclerotia of Monilinia vaccinii-corymbosi, which causes mummy berry disease of blueberry, was investigated. In two laboratory experiments, pseudosclerotia collected from rabbiteye blueberry in Georgia were conditioned at 5 to 6°C for 26 to 1,378 h prior to placement in conditions favorable for germination and apothecium development. The number of chill-hours accumulated during the conditioning period affected the subsequent proportion of pseudosclerotia that germinated and produced apothecia, with the greatest incidence of carpogenic germination occurring after intermediate levels of chilling (≈700 chill-hours). The minimum chilling requirement for germination and apothecium production was considerably lower than that reported previously for pseudo-sclerotia from highbush blueberry in northern production regions. The rate of carpogenic germination was strongly affected by interactions between the accumulation of chill-hours and degree-days during the conditioning and germination periods; pseudosclerotia exposed to prolonged chilling periods, once transferred to suitable conditions, germinated and produced apothecia more rapidly (after fewer degree-days had accumulated) than those exposed to shorter chilling periods. Thus, pseudosclerotia of M. vaccinii-corymbosi are adapted to germinate carpogenically following cold winters (high chill-hours, low degree-days) as well as warm winters (low chill-hours, high degree-days). Results were validated in a combined field-laboratory experiment in which pseudosclerotia that had received various levels of natural chilling were allowed to germinate in controlled conditions in the laboratory, and in two field experiments in which pseudosclerotia were exposed to natural chilling and germination conditions. A simple model describing the timing of apothecium emergence in relation to cumulative chill-hours and degree-days was developed based on the experiments. The model should be useful for better timing of field scouting programs for apothecia to aid in management of primary infection by M. vaccinii-corymbosi.

Communication Metrics for Human-Autonomy Teaming: Lessons Learned from us Army Gunnery Field Experiments

2021 ◽  
Vol 65 (1) ◽  
pp. 1157-1161
Author(s):  
Anthony L. Baker ◽  
Sean M. Fitzhugh ◽  
Daniel E. Forster ◽  
Kristin E. Schaefer
Keyword(s):  
Field Experiments ◽  
Autonomous Systems ◽  
Lessons Learned ◽  
Critical Window ◽  
Us Army ◽  
Communication Assessment ◽  
Human Autonomy ◽  
Communication Flow ◽  
And Performance ◽  
Carry Over

The development of more effective human-autonomy teaming (HAT) will depend on the availability of validated measures of their performance. Communication provides a critical window into a team’s interactions, states, and performance, but much remains to be learned about how to successfully carry over communication measures from the human teaming context to the HAT context. Therefore, the purpose of this paper is to discuss the implementation of three communication assessment methodologies used for two Wingman Joint Capabilities Technology Demonstration field experiments. These field experiments involved Soldiers and Marines maneuvering vehicles and engaging in live-fire target gunnery, all with the assistance of intelligent autonomous systems. Crew communication data were analyzed using aggregate communication flow, relational event models, and linguistic similarity. We discuss how the assessments were implemented, what they revealed about the teaming between humans and autonomy, and lessons learned for future implementation of communication measurement approaches in the HAT context.

scholarly journals Planning MAR Schemes Using Physical Models: Comparison of Laboratory and Field Experiments

2019 ◽  
Vol 9 (18) ◽  
pp. 3652
Author(s):  
Jana Sallwey ◽  
Felix Barquero ◽  
Thomas Fichtner ◽  
Catalin Stefan
Keyword(s):  
Vadose Zone ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Managed Aquifer Recharge ◽  
Physical Models ◽  
Aquifer Recharge ◽  
Operational Parameters ◽  
Flow Processes ◽  
Models Comparison ◽  
Other Regarding

Infiltration experiments in the context of managed aquifer recharge (MAR) are often conducted to assess the processes influencing the operation of full-scale MAR schemes. For this, physical models such as laboratory experiments and, less often, field experiments are used to determine process specifics or operational parameters. Due to several assumptions, scale-related limitations, and differing boundary conditions, the upscaling of results from the physical models is not straightforward. Investigations often lead to over- or underestimations of flow processes that constrain the translation of results to field-like conditions. To understand the restrictions and potential of different physical models for MAR assessment, surface infiltration experiments in different scales and dimensions, which maintained the same operational parameters, were conducted. The results from the different setups were compared against each other regarding the reproduction water flow in the vadose zone and the influence of parameters such as soil type and climate. Results show that mostly qualitative statements can be made, whereas quantitative analysis through laboratory experiments is limited.

Denitrification and immobilisation in flood-irrigated alkaline grey clays as affected by nitrification inhibitors, wheat straw, and soil texture

Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 633 ◽  
Author(s):  
I. J. Rochester ◽  
G. A. Constable
Keyword(s):  
Wheat Straw ◽  
Soil Texture ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Clay Content ◽  
Field Capacity ◽  
Nitrification Inhibitors ◽  
N Loss ◽  
Waterlogged Soil ◽  
Nitrate N

Published field studies have shown that etridiazole and other nitrification inhibitors may significantly improve N fertiliser recovery in alkaline grey clays. Laboratory experiments were conducted to examine the extent to which nitrification inhibitors could suppress denitrification directly in waterlogged soil, and determine whether this may contribute significantly to the conservation of N fertiliser in the field. Etridiazole reduced the loss of added nitrate-N from waterlogged soil in the short term (days) only. All other nitrification inhibitors failed to suppress N loss. Little nitrate-N was lost from soil maintained at field capacity, whereas 15–85% of applied nitrate was lost from soil that was waterlogged for 10 days. The addition of milled wheat straw encouraged both denitrification and biological N immobilisation to similar extents, although both processes were probably restricted by C availability. Where no straw was added, little N was immobilised and denitrification was halved. Soil texture (clay content) also had a profound influence on N fertiliser recovery (N loss). The laboratory experiments indicated that a component of the responses to etridiazole observed in published field experiments conducted on these soils could be attributed to direct suppression of denitrification by etridiazole.

Methodologies for Evaluating and Qualifying External Pipeline Coatings for Northern Pipelines

2006 ◽  
Author(s):  
S. Papavinasam ◽  
A. Doiron ◽  
T. Panneerselvam ◽  
Y. Lafrenie`re ◽  
M. Attard ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Low Temperatures ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Climatic Conditions ◽  
Limited Data ◽  
The North

The design of coatings must be adequate to protect pipelines under long-term, severe environmental conditions, including the extreme climatic conditions that will apply in the North before the pipe is installed and operation begins. Practices and standardised methodologies for evaluating and qualifying pipeline coatings for application in northern pipelines are discussed. Results from laboratory and field experiments, carried out under the conditions to which coatings will be exposed during construction, are presented. Based on 1-year laboratory experiments in which samples were exposed to temperatures as low as −45°C and limited data from the field experiments, it is concluded that Canadian Standards Association (CSA) standards CSA Z662, CSA Z245.20 and CSA Z245.21 adequately cover evaluation of coatings for northern pipelines. However, in order to evaluate the effects of low-temperatures, the specimens should be exposed for at least 4 months. Coatings qualified by CSA Z245.21 (System B1 and B2) are less affected from exposure to low-temperatures than those qualified by CSA Z245.21 (System A1) and CSA Z245.20.

8. Experimental Research

2017 ◽  
Author(s):  
Sandra Halperin ◽  
Oliver Heath
Keyword(s):  
Experimental Design ◽  
Research Design ◽  
Experimental Research ◽  
External Validity ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Ethical Issues ◽  
Natural Experiments ◽  
The Common ◽  
Internal And External Validity

This chapter explores the principles of experimental research design as well as the issues and problems associated with different aspects of the approach. In particular, it considers the issue of internal and external validity, the common obstacles associated with experimental research, and what can be done to try and avoid or minimize them. The chapter first describes the five steps involved in the classic version of the experimental design before discussing three types of experimental design: laboratory experiments, field experiments, and natural experiments. It also examines the ethical issues that arise from experimental research and concludes by highlighting some of the advantages of experimental research.

The Antibiotic Effects of Plants in Laboratory and Field

Weed Science ◽  
1972 ◽  
Vol 20 (2) ◽  
pp. 189-194 ◽  
Author(s):  
G. W. Selleck
Keyword(s):  
Laboratory Experiments ◽  
Field Experiments ◽  
Growth Habit ◽  
Leafy Spurge ◽  
Bare Ground ◽  
Vegetative Development ◽  
Marked Inhibition ◽  
Small Everlasting ◽  
Germinating Seeds ◽  
Antennaria Microphylla

In laboratory experiments, plant extracts of small everlasting (Antennaria microphylla Rydb.), field pussytoes (A. neglecta Greene), and leafy spurge (Euphorbia esula L.) were toxic to germinating seeds. Extracts of small everlasting inhibited vegetative development of leafy spurge, and soil taken from the immediate vicinity of roots inhibited germination and radicle elongation of germinating seeds of some species. Small everlasting competes vigorously with leafy spurge, and this competition cannot be attributed to morphology and growth habit. It suppressed vegetative growth of leafy spurge from rhizome sections in which the two species were competing in pots. In field experiments, this shallow-rooted, lowgrowing plant exhibited a marked inhibition on the growth of the vigorous, deep-rooted perennial, leafy spurge, as did the soil in which small everlasting had been growing. Antibiotic competition appears to be significant with the Antennaria spp., and the paucity of forbs in patches of leafy spurge, even when bare ground is visible between shoots, suggests that this species also exerts antibiotic effects on other plants. Allelopathy is probably a significant influence in interspacial relationships of species in most plant communities. A fuller knowledge of these relationships and their causes could lead to the utilization of this phenomenon in weed control.

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