STATISTICAL TESTS OF THE ACCURACY OF ALTERNATIVE FORECASTS: SOME RESULTS FOR U.S. UTILITY BETAS

The common approach for assessing the relative forecast accuracy of various predictors is simply to compare their simple ranks based on some measure(s) of forecast accuracy (such as the mean square errors). However, conventional methodologies for conducting a t-test or F-test of forecast accuracy are inappropriate and unreliable. A statistical methodology is proposed in this paper that rectifies most of the problems involved with conducting such conventional tests of statistical significance. Using this statistical methodology on the mean square errors of six beta predictors for five forecast horizons for fifty utilities, it was found that there are statistically significant differences between the forecast accuracies of the beta predictors for each and every forecast horizon, that the statistical rankings of the beta predictors were significantly different from and more congruent than the simple rankings as the forecast horizon lengthened, and that the ordinary least squares predictor was consistently ranked as one of the poorest beta predictors for all of the forecast horizons.     

哈佛大学：日本失落的十年值得中国反思

为了思考这一问题——如何让美好时光永驻,巩固并延续目前已经取得的成就,我们从过去20年日本的教训中可以找到一些堪为中国借鉴的方面。20年前的日本人肯定没有想到在其后的20年里日本经济所发生的一切。     

Cooperation,stability and social welfare under majority rule

We resolve collective irrationality in the stability set, a solution concept for voting games proposed by Rubinstein (J Econ Theory 23:150–159, 1980) to resolve the well-known paradox of voting in the core. A lack of cooperation within winning coalitions prevents their members from eliminating an alternative globally less preferred to another one when they observe the rational behavior defining the stability set. Allowing for the possibility of accompanying a coalitional vote with a binding solidarity agreement is a natural response to this cooperation failure. This leads to a new standard of behavior and a new solution concept called stability set with binding solidarity agreement or S _c -stability set. It is shown that the S _c -stability set and a newly defined version of the Mas-Colell bargaining set for simple games are not comparable with respect to set inclusion. The S _c -stability set includes the core, is included in the stability set and contains only Pareto-optimal alternatives. When individual preferences are complete linear orders, the S _c -stability set is always non-empty.      

Treatment patterns among patients with psoriasis using a large national payer database in the United States: a retrospective study

Aim: To characterize treatment patterns of psoriasis patients in a large US managed care database.

Materials and methods: Adults with newly-diagnosed psoriasis were identified from July 3, 2006–August 31, 2014. Patients had continuous enrollment with medical and pharmacy benefits for ≥6 months prior to and ≥1 year following the index date. The index date was the point at which any of the following inclusion criteria were satisfied: first psoriasis diagnosis by a dermatologist, ≥ 2 psoriasis diagnoses ≥30 days apart, or a diagnosis of psoriasis followed by a claim for psoriasis therapy. Of primary interest was to measure and describe the following psoriasis treatment patterns: utilization rates, time to treatment discontinuation, and lines of therapy for various therapeutic classes of pharmacologic therapies.

Results: From the 128,308 patients identified, 53% were female, mean?±?SD age was 50?±?16 years, with median 3 years follow-up. Topicals were received by 86% of patients, non-biologic systemics by 13%, biologics by 6%, phototherapy by 5%, and 13% received no psoriasis-related medication. Median time from index to first treatment was 0 days for topical, 6 months for non-biologic systemic, and 6 months for biologic. Of those treated, first-line therapies included topical (95%), non-biologic systemic (4%), and biologic (2%). For those with second-line treatment, non-biologic systemic (71%) and biologic (30%) therapies were more common. The most common treatment pattern was topicals only (83%), while all other patterns comprised <5% of the treatment patterns observed.

Limitations: Like other observational studies, limitations to consider when interpreting results include the 6-month pre-index period of no psoriasis or the psoriasis medication claim may not perfectly select only incident user of psoriasis medications, claims-based algorithms may not accurately represent true treatment patterns, absence of over-the-counter medications data, and having no trend analyses over time or between groups.

Conclusions: While the majority of patients with psoriasis initiated a pharmacological therapy, a significant portion did not have a claim for any psoriasis medication. Topical treatments are the most commonly used treatments for psoriasis. Non-biologic systemic and biologic therapies were rarely used first line, but became more common in later lines of treatment.     

Perceptions of management difficulty factors by expatriate hotel professionals in China

Successful overseas hotel operations depend on technically competent and culturally adaptable expatriate managers. This study reveals that expatriate hotel professionals from many different countries are now working in China. It examines and analyses the perceptions of six management difficulty factors by the expatriate hotel professionals. Staff attitude and lack of competence of the local managers are identified as the most difficult management factors, followed by language barriers, cultural differences and lack of local management support. Government policy change is perceived as the least difficult factor. The empirical findings of this study can be used by the Chinese tourism authority to improve the business environment for foreign investment and management; and by multinational hotel corporations to strengthen training programs in preparing expatriate managers for management assignments in China.