We conducted the first randomized controlled field experiment of an Internet reputation mechanism. A high-reputation, established eBay dealer sold matched pairs of lots— batches of vintage postcards—under his regular identity and under new seller identities (also operated by him). As predicted, the established identity fared better. The difference in buyers’ willingness-to-pay was 8.1% of the selling price. A subsidiary experiment followed the same format, but compared sales by relatively new sellers with and without negative feedback. Surprisingly, one or two negative feedbacks for our new sellers did not affect buyers’ willingness-to-pay.

For autoregressive time series with positive innovations which either have heavy right or left tails, linear programming parameter estimates of the autoregressive coefficients have good rates of convergence. However, the asymptotic distribution of the estimators depends heavily on the distribution of the process and thus cannot be used for inference. A bootstrap procedure circumvents this difficulty. We verify the validity of the bootstrap and also give some general comments on the bootstrapping of heavy tailed phenomena.

Teflon® AF is a family of amorphous fluoropolymers with glass transition temperatures as high as 300° based on bis-2,2-trfluoromethyl-4,5-difluoro-1,3-dioxole, (I), which has unusual properties [1–3] (Figure 1). The family retains the superior electrical, chemical resistance and thermal properties associated with fluoropolymers. In addition the polymers have high optical clarity, limited solubility in some commercially available perfluorinated ethers such as Fluorinert® FC-75 and improved physical properties below their glass transition temperatures (Figure 2). Teflon® AF polymers may be either solution cast into clear micron thin films or melt processed into a variety of forms.