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This paper shows how to bootstrap hypothesis tests in the context of the Parks’s (1967) Feasible Generalized Least Squares estimator. It then demonstrates that the bootstrap outperforms FGLS(Parks)’s top competitor. The FGLS(Parks) estimator has been a workhorse for the analysis of panel data and seemingly unrelated regression equation systems because it allows the incorporation of cross-sectional correlation together with heteroskedasticity and serial correlation. Unfortunately, the associated, asymptotic standard error estimates are biased downward, often severely. To address this problem, Beck and Katz (1995) developed an approach that uses the Prais-Winsten estimator together with “panel corrected standard errors” (PCSE). While PCSE produces standard error estimates that are less biased than FGLS(Parks), it forces the user to sacrifice efficiency for accuracy in hypothesis testing. The PCSE approach has been, and continues to be, widely used. This paper develops an alternative: a nonparametric bootstrapping procedure to be used in conjunction with the FGLS(Parks) estimator. We demonstrate its effectiveness using an experimental approach that creates artificial panel datasets modelled after actual panel datasets. Our approach provides a superior alternative to existing estimation options by allowing researchers to retain the efficiency of the FGLS(Parks) estimator while producing more accurate hypothesis test results than the PCSE.

This article extends the analysis of durability in several directions. The choice of durability may be related to other aspects of the cost of using the good in addition to the economic life. Transaction costs are introduced as an important feature in markets for durable goods, and the effect of transaction costs on the demand for durables is derived. The relationship between durability and parameters of the operating cost structure is developed. Moreover, the marginal utility of consumption at any point in time for either type of good must be proportional to the appropriate forward price.

Presents a commentary to criticism made on a study about vertical equity in real estate assessment. Criterion for evaluating assessment performance; Aspects of error in the development of the assessment procedures; Discussion of the issue of repeated sampling.

This paper considers assets whose service flow decays at a rate determined by built-in durability and the level of maintenance. A cost minimization model determines optimal durability and maintenance and shows how these variables respond to changes in interest rates, the price of maintenance, and the cost of new assets. The price of old assets adjusts so that the cost of services from both old and new assets is the same. The model provides a framework for analyzing data on automobile scrapping rates and repair expenditures. Data for postwar United States show that scrapping rates are sensitive to the price of repairs relative to the price of new cars. The amount of repairs per car also responds to the relative repair price. [ABSTRACT FROM AUTHOR]

Comments on author Daniel F. Kohler's article on homothetic restriction of preferences. Introduction of the assumption of an homothetically separable utility function; Discussion on recent attempts to analyze the demand for electricity by time of use; Information on Kohler's random demand model and Monte Carlo experiment.

Cancer is one of the leading causes of death in the U.S., and tumorous cancers such as cervical, lung, breast, and ovarian cancers are the most common types. APOBEC3B is a nonessential cytidine deaminase found in humans and theorized to defend against viral infection. However, overexpression of APOBEC3B is linked to cancer in humans, which makes APOBEC3B a potential cancer treatment target through competitive inhibition for several tumorous cancers. Computational studies can help reveal a small molecule inhibitor using high-throughput virtual screening of millions of candidates with relatively little cost. This study aims to narrow the field of potential APOBEC3B inhibition candidates for future in vitro assays and provide an effective scaffold for drug design studies. Another goal of this project is to provide critical amino acid targets in the active site for future drug design studies. This study simulated 7.8 million drug candidates using high-throughput virtual screening and further processed the top scoring 241 molecules from AutoDock Vina, DOCK 6, and de novo design. Using virtual screening, de novo design, and molecular dynamics simulations, a competitive inhibitor candidate was discovered with an average binding free energy score of -46.03 kcal/mol, more than 10 kcal/mol better than the substrate control (dCMP). These results indicate that this molecule (or a structural derivative) may be an effective inhibitor of APOBEC3B and prevent host genome mutagenesis resulting from protein overexpression. Another important finding is the confirmation of essential amino acid targets, such as Tyr250 and Gln213 within the active site of APOBEC3B. Therefore, study used novel computational methods to provide a theoretical scaffold for future drug design studies that may prove useful as a treatment for epithelial cancers.Communicated by Ramaswamy H. Sarma.