Error by design: Methods for predicting device usability

This paper introduces the idea of predicting ‘designer error’ by evaluating devices using Human Error Identification (HEI) techniques. This is demonstrated using Systematic Human Error Reduction and Prediction Approach (SHERPA) and Task Analysis For Error Identification (TAFEI) to evaluate a vending machine. Appraisal criteria which rely upon user opinion, face validity and utilisation are questioned. Instead a quantitative approach, based upon signal detection theory, is recommended. The performance of people using SHERPA and TAFEI are compared with heuristic judgement and each other. The results of these studies show that both SHERPA and TAFEI are better at predicting errors than the heuristic technique. The performance of SHERPA and TAFEI are comparable, giving some confidence in the use of these approaches. It is suggested that using HEI techniques as part of the design and evaluation process could help to make devices easier to use

Insect diversity and abundance within the canopy of a northern red oak (Quercus rubra L.) orchard in eastern Tennessee

The Watauga northern red oak (NRO) (Quercus rubra L.) seed orchard was established in 1987 by the USDA Forest Service in Johnson County, TN. Originally a genetic test of 220 open-pollinated families, these trees now serve as a seed source for oak reforestation efforts. Acorn production in the seed orchard has been partially limited due to premature abscission of flowers and immature acorns. The cause of this production loss is unknown, although canopy-dwelling insects have been implicated. To better understand the insect communities existing in the canopy of the seed orchard, a two-year insect diversity study was conducted in 1992 and 1993. The crowns of 20 trees in five genetic families were sampled for insects approximately every two weeks from March to November. Adult insect populations collected on each NRO family were analyzed statistically for significant differences. In the two years, 26,536 adult insect specimens were collected, representing 15 orders. Within these orders, 143 families and 541 species have been identified (as of 12/1/94). These numbers suggest a diverse, well-established insect community within the seed orchard. Of the insects collected, the Asiatic oak weevil (Cyrtepistomus castaneus Roelofs) was the most abundant species, composing 25% of all specimens collected. Other important pests found in the seed orchard were acorn weevils in the genus Curculio and Platycotis vittata P., an oak treehopper. The overall insect communities collected from each NRO genetic family did not differ significantly. But significant differences were found in populations of certain pest species among NRO families. These variations indicate that genetic differences among NRO families do have an effect on pest populations. Based on these comparisons, and other factors such as acorn production, NRO families suitable for use in reforestation efforts were identified. NRO Family #200, originating in Limestone Co., AL, demonstrated the most potential for use in the regeneration and reforestation of NRO in the southern Appalachians. This research has uncovered a very diverse insect community in the canopy of an eastern Tennessee NRO seed orchard. Of these insect species, relatively few (ca. 8%) are pests on the trees. These pest populations did differ among the NRO families, suggesting that NRO genetics influence pest densities. Further research is needed to determine how these insect pests affect the trees and how NRO genetics affect the pests

Landing the first job: the value of intermediaries in online hiring

Online markets for remote labor services allow workers and firms to contract with each other directly. Despite this, intermediaries - called outsourcing agencies - have emerged in these markets. This paper shows that agencies signal to employers that inexperienced workers are high quality. Workers affiliated with an agency have substantially higher job-finding probabilities and wages at the beginning of their careers compared to similar workers without an agency affiliation. This advantage declines after high-quality non-affiliated workers receive good public feedback scores. The results indicate that intermediaries have arisen endogenously to permit a more efficient allocation of workers to jobs

Landing the first job: the value of intermediaries in online hiring

Online markets for remote labour services allow workers and firms to contract with each other directly. Despite this, intermediaries—called outsourcing agencies—have emerged in these markets. This article shows that agencies signal to employers that inexperienced workers are high quality. Workers affiliated with an agency have substantially higher job-finding probabilities and wages at the beginning of their careers compared to similar workers without an agency affiliation. This advantage declines after high-quality non-affiliated workers receive good public feedback scores. The results indicate that intermediaries have arisen endogenously to permit a more efficient allocation of workers to jobs

Different strokes for different folks? Revealing the physical characteristics of smartphone users from their swipe gestures

Anthropometrics show that the lengths of many human body segments follow a common proportional relationship. To know the length of one body segment - such as a thumb - potentially provides a predictive route to other physical characteristics, such as overall standing height. In this study, we examined whether it is feasible that the length of a person’s thumb could be revealed from the way in which they complete swipe gestures on a touchscreen-based smartphone.From a corpus of approx. 19000 swipe gestures captured from 178 volunteers, we found that people with longer thumbs complete swipe gestures with shorter completion times, higher speeds and with higher accelerations than people with shorter thumbs. These differences were also observed to exist between our male and female volunteers, along with additional differences in the amount of touch pressure applied to the screen.Results are discussed in terms of linking behavioural and physical biometrics. Keywords: Touchscreen gestures, behavioral biometrics, physical biometrics<br/

Beyond zeroes and ones: the severity and evolution of civil conflict

We assess risk factors affecting the severity and dynamics of civil wars, departing from analyses focused primarily on static models of the effect of income on the extensive margin of conflict. Civil conflicts are shown to be persistent, but rarely do they become more severe in response to past fighting. Substantial heterogeneity in the speed of mean reversion is documented: severe fighting lasts longest in poor countries and ethnically fractionalized countries

Information spillovers in experience goods competition

Trialing an experience good allows consumers to learn their value for the sampled good and also informs beliefs about their value for similar products. These demand-side information spillovers across products create a relatively well-informed group of potential future consumers for rival firms. When both switching consumers and repeat buyers are profitable, firms face reduced incentives to set a low initial price to attract inexperienced consumers. Switchers and repeat buyers are more likely to be profitable in new product categories that build on major innovations and when firms can price discriminate based on purchasing history. We suggest that competing products and services arising from new innovations often have demand-side information spillovers from any product trial and are, hence, settings where competing firms can make overall profits even when selling products that consumers perceive to be indistinguishable prior to initial trial

Distinguishing Observed Inattentive Behaviors in the College Classroom as they Correlate to Brain Wave Activity Utilizing a Wireless Electroencephalograph

A significant amount of research has been devoted to the behavioral correlates of inattention in children (A.P.A., 2000; Arnold, 2000; Gordon & Barkley, 1998). It is proposed by the authors that college students, in their several years of experience, are much more capable of masking these trademark behaviors. When a child loses interest they will begin to openly look around the room, shift in their seat, or chat with their neighbors (Sandberg, Rutter & Taylor, 1978; Arnold, 2000). College students however, are proposed to candidly fidget, shift in their seat, or even maintain eye contact with their instructor while “daydreaming”. Therefore, an additional physiological aid is required to better assess inattentive periods in college subjects. Given the invasive nature of past devices commonly used, such as the Electroencephalograph (EEG), accurate measurement proves to be very difficult in a natural setting (Boyd & Campbell, 1998). This study used a modified version of an EEG called the Attention Trainer (AT). The AT is smaller in size, and wireless thus alleviating distraction and allowing more reliable field assessment. The study found positive correlations (Table 1) between suggested and previously validated behaviors. Contrary to prior research, significant correlations were found between all four frequency bands (Beta, Theta, Delta, and SMR), suggesting the device may be inaccurate (Figure 1). While results can neither confirm nor discredit biofeedback applications for the AT, further research is needed for validation