Tong Zeng

This research uses quasi-Monte Carlo sampling experiments to examine the properties of pretest and positive-part Stein-like estimators in the random parameters logit (RPL) model based on the Lagrange Multiplier (LM), likelihood ratio (LR) and Wald tests. First, we explore the properties of quasi-random numbers, which are generated by the Halton sequence, in estimating the random parameters logit model. We show that increases in the number of Halton draws influence the efficiency of the RPL model estimators only slightly. The maximum simulated likelihood estimator is consistent and it is not necessary to increase the number of Halton draws when the sample size increases for this result to be evident. In the second essay, we study the power of the LM, LR and Wald tests for testing the random coefficients in the RPL model, using the conditional logit model as the restricted model, since we found that the LM-based pretest estimator provides the poor risk properties. We claimed that the power of LR and Wald tests decreases with increases in the mean of the coefficient distribution. The LM test has the weakest power for presence of the random coefficient in the RPL model. In the last essay, the pretest and shrinkage are showed to reduce the risk of the fully correlated RPL model estimators significantly. The percentage of correct predicted choices is increased by 2% using the positive-part Stein-like estimates compared to the results using the pretest and fully correlated RPL model estimates with using the marketing consumer choice data.

Mycoheterotrophic plants can derive carbon from fungi rather than from photosynthesis. Habitat destruction and sensitivity to environmental perturbation may result in the loss of biodiversity including genetic variation of mycoheterotrophic plants. Burmannia nepalensis (Miers) Hook.f. (Burmanniaceae) is a mycoheterotrophic plant with a wide distribution across southern China and southern and eastern Asia. As part of our endeavor to reveal population genetic patterns of mycoheterotrophic plants, fifteen microsatellite loci were developed by RAD (restriction site-associated DNA) sequencing in 89 individuals from four populations of B. nepalensis. A total of 49 alleles were amplified. The number of alleles per locus ranged from two to six with an average of 3.3. The observed and expected heterozygosity per population varied from 0.000 to 1.000 and from 0.000 to 0.722, respectively. A transferability test showed that only one to five loci could be cross-amplified successfully in four other congeneric species of Burmannia. These markers can be used to reveal population genetic diversity in B. nepalensis, and will help to elucidate the evolutionary history and to enhance efforts for conservation of mycoheterotrophic plants.

Based on the in-depth implementation of the strategy of "network power", the Internet plus thinking has been integrated into every field of social construction, especially in the field of financial management, which has provided great convenience for the depreciation management of fixed assets, and also made depreciation more and more important. Based on the digital background, this paper analyzes the problems existing in the depreciation of fixed assets in China from the aspects of acquisition, maintenance, treatment and management of fixed assets. At the same time, in order to improve the quality of fixed assets depreciation management under the background of digitization, enterprises need to scientifically select depreciation methods for digital application in fixed assets management based on conditional support, optimize fixed assets management methods with digitalization, strengthen the skills training of fixed assets management personnel, encourage enterprises to reasonably avoid taxes, and increase the management of fixed assets depreciation by the society The supervision strength.

A citation is a well-established mechanism for connecting scientific artifacts. Citation networks are used by citation analysis for a variety of reasons, prominently to give credit to scientists' work. However, because of current citation practices, scientists tend to cite only publications, leaving out other types of artifacts such as datasets. Datasets then do not get appropriate credit even though they are increasingly reused and experimented with. We develop a network flow measure, called DataRank, aimed at solving this gap. DataRank assigns a relative value to each node in the network based on how citations flow through the graph, differentiating publication and dataset flow rates. We evaluate the quality of DataRank by estimating its accuracy at predicting the usage of real datasets: web visits to GenBank and downloads of Figshare datasets. We show that DataRank is better at predicting this usage compared to alternatives while offering additional interpretable outcomes. We discuss improvements to citation behavior and algorithms to properly track and assign credit to datasets.

In this paper, we apply the fully correlated random parameters logit (FCRPL) model to the genetic carrier testing data using shrinkage estimation. We show that shrinkage estimates with higher shrinkage constant improve the percentages of correct predicted choices by 2% and 10% respectively with Jewish and general population samples. The mean estimates of elasticity based on the shrinkage estimates are closer to those with the FCRPL model estimates and have smaller standard errors than the corresponding results based on the uncorrelated random parameters logit model estimates.

Based on the urban box theory model, a maximum limit model for vehicle exhaust emissions was established to determine the maximum limit of NO_X emissions in Shenyang. Based on the model for calculating the appropriate level of vehicle ownership in Shenyang City, the vehicle ownership was calculated under different standards, promoting the grey prediction of motor vehicle ownership in Shenyang city. Studying the appropriate level of motor vehicle ownership in Shenyang city can help reduce urban traffic pollution to a greater extent and ensure people’s happy life.

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