Benjamin Chan

Learn More
<i>Do improvements in system performance demonstrated by batch evaluations confer the same benefit for real users? We carried out experiments designed to investigate this question. After identifying a weighting scheme that gave maximum improvement over the baseline in a non-interactive evaluation, we used it with real users searching on an instance recall(More)
Two common assumptions held by information retrieval researchers are that searching using Boolean operators is inferior to natural language searching and that results from batch-style retrieval evaluations are generalizable to the real-world searching. We challenged these assumptions in the Text Retrieval Conference (TREC) interactive track, with real users(More)
Studies comparing Boolean and natural language searching with actual end-users are still inconclusive. The TREC interactive track provides a consensus-developed protocol for assessing this and other user-oriented information retrieval research questions. We recruited 28 experienced information professionals with library degrees to participate in this year's(More)
Orthotopic liver retransplantation (re-OLT) is highly controversial. The objectives of this study were to determine the validity of a recently developed United Network for Organ Sharing (UNOS) multivariate model using an independent cohort of patients undergoing re-OLT outside the United States, to determine whether incorporation of other variables that(More)
In the TREC-8 Interactive Track, our results indicated that the better performance obtained in batch searching evaluation do not translate into better performance by users in an instance recall task. This year we pursued this investigation further by performing the same experiments using the new question-answering task adopted in the TREC-9 Interactive(More)
HLA-restricted immune escape mutations that persist following HIV transmission could gradually spread through the viral population, thereby compromising host antiviral immunity as the epidemic progresses. To assess the extent and phenotypic impact of this phenomenon in an immunogenetically diverse population, we genotypically and functionally compared(More)
The purpose of this study is to investigate the purchase decision of Malaysian Generation Y and its association with brand concern, convenience concern, dependency concern, price concern, product feature concern and social influence concern. The data set is collected through self-administered questionnaire, and convenient non-probability random sampling(More)
This research studied a special-needs population under age 18 who had both private insurance and Medicaid coverage through the Tax Equity and Fiscal Responsibility Act of 1982 (TEFRA) option. We found that children with managed care plans, particularly health maintenance organizations (HMOs), tended to incur higher total expenses to TEFRA than children with(More)
  • 1