A trend filtering method closely related to $$\ell _{1}$$ trend filtering

The filtering method developed by Kim et al. (SIAM Rev 51:339–360, 2009), \(\ell _{1}\) trend filtering, is attractive because it enables us to estimate a continuous piecewise linear trend. This paper introduces a new filtering method closely related to \(\ell _{1}\) trend filtering in order to contribute to the accumulation of knowledge on \(\ell _{1}\) trend filtering. We show that the piecewise linearity, which is the key feature of \(\ell _{1}\) trend filtering, is derived from the new filtering. For this reason, we refer to the filtering as ‘pure’ \(\ell _{1}\) trend filtering. We also demonstrate some other miscellaneous results concerning the new filtering.     

The association between smoking cessation outpatient visits and total medical costs: a retrospective,observational analysis of Japanese employee-based public health insurance data

Aims: The short-term effects of smoking cessation (SC) on overall healthcare costs are unclear. This study aimed to compare the short-term medical costs between patients with SC outpatient visits (SCOVs) and those without SCOVs, consisting of SCOV itself and overall medical costs.

Materials and methods: This study is a retrospective, observational study using a Japanese employee-based health insurance claims database (January 1, 2005–December 31, 2013). It analyzed individuals who were registered as smokers based on their medical checkup details. It compared the per-patient-per-year (PPPY) medical costs for male smokers who made ≥1 claim for SCOVs with those who made no claims. We also assessed whether the number of SCOVs by male and female smokers impacted medical costs. The Index Year was the year after the first SCOV claim and that after the first registration as a smoker (non-SCOV group). Medical costs were calculated using regression analysis and adjusted for baseline costs.

Results: In Index Year ?1, PPPY medical costs for male smokers were ～USD 323.01 (JPY 36,500, as of November 2017) higher in the SCOV (n?=?5,608) vs the non-SCOV (n?=?81,721) group; however, by Year 6 the costs were similar. From Year 4–6, PPPY medical costs for SCOVs were lower than those in the adjusted non-SCOV group. For 2,576 male and female smokers in the SCOV group, the average rates of increasing medical costs before and after the SCOV for 1, 2, 3, 4, and 5 SCOVs made were 58%, 44%, 50%, 41%, and 34%, respectively.

Limitations: The database includes limited data on individuals >65 years. Only SCOVs based on claims data and not on other outcomes were assessed.

Conclusions: Medical costs declined in the short-term following the first SCOV. Attendance at a greater number of SCOVs was associated with a lower increase ratio of medical costs.     

Cointegration and spatial price transmission among wheat and wheat-flour markets in Afghanistan

This article examines cointegration and spatial price transmission among Afghan wheat and flour markets as well as their linkages with those of supplier countries and global markets. Unit root tests, consistent momentum threshold autoregressive (M-TAR) models and vector error correction models (asymmetric and symmetric) are employed to achieve research objectives. The results suggest that provincial wheat and flour markets may have a long-run relationship with principal market of Kabul. Afghan wheat and flour markets may also be cointegrated with their respective global, Kazakh and Pakistani markets. While provincial wheat markets might adjust to divergence from their long-run equilibrium with Kabul wheat market, some of the provincial flour markets may not respond to deviation from their long-run equilibrium with Kabul flour market. The speed of adjustment towards the long-run Afghan–Pakistani and Afghan–Kazakh equilibrium may be faster for Afghan flour than wheat markets. The equilibrium adjustment coefficients are generally small and market imperfections may exist, however. A shock in Kabul wheat and flour markets may have long-lasting effect on the respective provincial markets whereas a shock in global wheat and Pakistani, and Kazakh wheat and flour markets might have transitory effect on the corresponding Afghan markets.     

Agency Contracts,Noncommitment Timing Strategies and Real Options

Given that an owner lacks the ability to commit to his or her timing decisions under a manager's hidden action, we consider the optimal design of the contract and the owner's optimal timing decisions. Using a real options approach, we show that, compared with the full commitment case, a higher (lower)‐quality project is launched later than (at the same time as) the first‐best case, whereas the replacement of the manager is (is not necessarily) made later if the hidden‐action problem is severe enough (is not severe enough). Severance pay may serve to minimize the compensation for the manager's loss of corporate control.     

Examining the association of smoking with work productivity and associated costs in Japan

Aims: Smoking is associated with significant health and economic burden globally, including an increased risk of many leading causes of mortality and significant impairments in work productivity. This burden is attenuated by successful tobacco cessation, including reduced risk of disease and improved productivity. The current study aimed to show the benefits of smoking cessation for workplace productivity and decreased costs associated with loss of work impairment.

Materials and methods: The data source was the 2011 Japan National Health and Wellness Survey (n?=?30,000). Respondents aged 20–64 were used in the analyses (n?=?23,738) and were categorized into: current smokers, former smokers, and never smokers. Generalized linear models controlling for demographics and health characteristics examined the relationship of smoking status with the Work Productivity and Activity Impairment questionnaire (WPAI-GH) endpoints, as well as estimated indirect costs.

Results: Current smokers reported the greatest overall work impairment, including absenteeism (i.e. work time missed) and presenteeism (i.e. impairment while at work); however, after controlling for covariates, there were no significant differences between former smokers and never smokers on overall work impairment. Current smokers and former smokers had greater activity impairment (i.e. impairment in daily activities) than never smokers. Current smokers reported the highest indirect costs (i.e. costs associated with work impairment); however, after controlling for covariates, there were no significant differences between former smokers and never smokers on indirect costs.

Limitations and conclusions: Smoking exerts a large health and economic burden; however, smoking cessation attenuates this burden. The current study provides important further evidence of this association, with former smokers appearing statistically indistinguishable from never smokers in terms of work productivity loss and associated indirect costs among a large representative sample of Japanese workers. This report highlights the workplace benefits of smoking cessation across productivity markers and cost-savings.     

Implementation of multi-agent incentive contracts with the principal's renegotiation offer

The purpose of this paper is to explore a mechanism for supporting desired equilibrium actions in a one-principal, multi-agent model when the principal makes a renegotiation offer. We show that there exists a mechanism in which the principal's most preferred mixed strategy is always supported. Received: 30 May 1997 / Accepted: 10 October 1998