On the online auction site eBay, by convention, sellers do not ship goods to winning bidders until after they have received payment, so there is an opportunity for sellers to take advantage of bidders' trust. Realizing this, the designers of eBay created a system that relies on self-enforcement using reputation. Several recent studies have found that bidders give little or no reward to sellers who have better reputations. I show that in fact, sellers are strongly rewarded for the first few reports that they have behaved honestly, but marginal returns to additional reports are severely decreasing. © 2005 President and Fellows of Harvard College and the Massachusetts Institute of Technology.

Over a 2-year period, 21 patients with clinical and radiologic evidence of persistent or recurrent frontal sinusitis who had a prior ethmoidectomy and/or frontal sinusotomy underwent an endoscopic Lothrop procedure. The patients' chief complaints were headaches (13), nasal obstruction and/or purulent rhinorrhea (4), orbital abscess/cellulitis (2), anosmia (1), and cough (1). Preoperative frontal headaches were present in 19 patients. The common frontal ostium remained patent (> 50% of intraoperative size) by flexible fiberoptic examination and transillumination 2-24 months postoperatively in 12 of 21 patients (57%). Eighteen of 21 patients (86%) had improved or resolved chief complaints. All but 4 of 19 patients (21%) with preoperative frontal headaches had improved or resolved symptoms. Two patients required additional surgery during the follow-up period. The endoscopic Lothrop procedure is a viable option before frontal sinus obliteration in patients with recurring frontal sinusitis who have failed conventional endoscopic techniques. The surgical technique and results will be presented.

US students often rank poorly on standardized tests that estimate and compare educational achievements. We investigate whether this might reflect not only differences in ability but also differences in effort on the test. We experimentally offer students incentives to put forth effort in two US high schools and four Shanghai high schools. US students improve performance substantially in response to incentives, while Shanghai students—who are top performers on assessments—do not. These results raise the possibility that ranking countries based on low-stakes assessments may not reflect only differences in ability, but also motivation to perform well on the test. (JEL C93, I21, I26, O15, P36)

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Prior research finds that controls that induce cooperation among collaborators on a project increase trust, and that this increased trust increases subsequent cooperation among collaborators. We extend this work by investigating how controls influence cooperative behavior in two settings. The first is an interactive setting where people work together and can benefit from each other's work. The second is a non‐interactive setting where people do not work together directly but where behavior can be observed. We propose that because controls are likely to engender greater trust and reciprocity in interactive settings than in non‐interactive settings, the effect of controls on future cooperative behavior will be greater for controls in interactive settings than for controls in non‐interactive settings. We find that controls in both settings increase future cooperative behavior, but the effect is significantly greater in interactive settings (where reciprocity and trust are more likely to develop). Furthermore, this increased cooperation is observed in an uncontrolled task, suggesting that the control fosters trust in others rather than trust in the control. These findings suggest that the benefits of controls are more substantial in work environments characterized by extensive teamwork and where employees benefit from each other's work.