Multivariate contemporaneous-threshold autoregressive models

This paper proposes a contemporaneous-threshold multivariate smooth transition autoregressive (C-MSTAR) model in which the regime weights depend on the ex-ante probabilities that latent regime-specific variables exceed certain threshold values. A key feature of the model is that the transition function depends on all the parameters of the model as well as on the data. Since the mixing weights are also a function of the regime-specific noise covariance matrix, the model can account for contemporaneous regime-specific co-movements of the variables. The stability and distributional properties of the proposed model are discussed, as well as issues of estimation, testing and forecasting. The practical usefulness of the C-MSTAR model is illustrated by examining the relationship between US stock prices and interest rates.     

Sharp IV Bounds on Average Treatment Effects on the Treated and Other Populations Under Endogeneity and Noncompliance

In the presence of an endogenous binary treatment and a valid binary instrument, causal effects are point identified only for the subpopulation of compliers, given that the treatment is monotone in the instrument. With the exception of the entire population, causal inference for further subpopulations has been widely ignored in econometrics. We invoke treatment monotonicity and/or dominance assumptions to derive sharp bounds on the average treatment effects on the treated, as well as on other groups. Furthermore, we use our methods to assess the educational impact of a school voucher program in Colombia and discuss testable implications of our assumptions. Copyright © 2015 John Wiley & Sons, Ltd.     

Bioenergie im globalen Energiesystem Möglichkeiten und Grenzen

Biomass as a source of energy becomes more and more important world wide. At the same time the demand for food and fodder as well as for renewable raw material is increasing significantly. On this background the goal of this paper is it to discuss based on a presentation of the world wide energy system the potentials of an energy provision from biomass and to discuss these potentials within the context of the dimensions of the global energy system. Based on these data statements are made under which circumstances the contribution of biomass within the energy system can be increased.     

Evaluating the risk of patent infringement by means of semantic patent analysis: the case of DNA chips

In this paper, we are going to present a method for detecting the risks of patent infringement by evaluating similarities between patent documents on the basis of semantic patent analysis. This approach enables the user to visualize similarities in the contents on a semantic patent map by means of multi‐dimensional scaling. The effectiveness of the semantic patent map has already been demonstrated by Dressler (2006) with regard to patents of seal technology, in which documents are commonly kept short and the extracted contents are concise. This paper will open out to the field of biotechnology, where patents can easily comprise several hundreds of pages. The method presented here conveys an interdisciplinary approach and combines computer‐aided natural language processing with domain‐specific expertise of biochemical processes. This is illustrated by an authentic case of infringement involving two manufacturers of DNA chips. Our experiment will show how the infringement case is visualized on a patent map based on semantic patent analysis. This experiment can be compared with the search for a needle in a haystack, the two competitive patents representing significantly conflicting ‘needles.’ From an approximate number of 4,000 patents in the current US Class 435/6, a set of patents was selected that included the ‘needles’ mentioned. This paper will point out how such mutual interference can be detected by way of semantic patent analysis, and what advice may be given to R&D managers who are faced with the risk of patent infringement.     

A real-world analysis of healthcare costs and relative risk of hyperprolactinemia associated with antipsychotic treatments in the United States

Abstract

Aims: Antipsychotic medications are associated with an increased risk of hyperprolactinemia, but differ in their propensity to cause this complication. This study aimed to assess the economic burden of hyperprolactinemia, and to compare its risk among adult patients using atypical antipsychotics (AAs) with a mechanism of action associated with no/low vs high/moderate prolactin elevation.

Methods: This retrospective cohort study was based on US Commercial and Medicaid claims databases. Healthcare costs were compared between matched hyperprolactinemia and hyperprolactinemia-free cohorts using a two-part model. Risk of hyperprolactinemia was compared between patients receiving AAs with a mechanism of action associated with no/low (no/low prolactin elevation cohort) vs high/moderate prolactin elevation (high/moderate prolactin cohort) using logistic regression.

Results: In the commercially insured sample, compared to the hyperprolactinemia-free cohort (n?=?499), the hyperprolactinemia cohort (n?=?499) was associated with incremental total healthcare costs of $5,732 ($20,081 vs $14,349; p?=?.004), and incremental medical costs of $3,861 ($13,218 vs $9,357; p?=?.040), mainly driven by hyperprolactinemia-related costs. In the Medicaid-insured sample, compared to the hyperprolactinemia-free cohort, the hyperprolactinemia cohort was associated with incremental total healthcare costs of $10,773 ($30,763 vs $19,990; p?=?.004), and incremental medical costs of $9,246 ($20,859 vs $11,613; p?=?.004), mainly driven by hyperprolactinemia-related and mental health-related costs. The odds of hyperprolactinemia in the no/low prolactin elevation cohort were 4–5-times lower than that in the high/moderate prolactin elevation cohort (odds ratio =0.21; p?<?.001).

Limitations: Hyperprolactinemia may be under-reported in claims data.

Conclusions: Hyperprolactinemia is associated with substantial healthcare costs. AAs associated with no/low prolactin elevation reduce the risk of hyperprolactinemia by 4–5-times compared to AAs associated with moderate/high prolactin elevation. Treatment options with minimal impact on prolactin levels may contribute to reducing hyperprolactinemia burden in AA-treated patients.     

Economic modeling to evaluate the impact of chronic myeloid leukemia therapy management on the oncology care model in the US

Abstract

Objective: To develop an economic model to evaluate changes in healthcare costs driven by restricting usage of branded tyrosine kinase inhibitors (TKIs) through substitution with generic imatinib among chronic myeloid leukemia (CML) patients in a typical Oncology Care Model (OCM) practice, and examine the impact on Performance-Based Payment (PBP) eligibility.

Methods: An Excel-based economic model of an OCM practice with 1,000 cancer patients during a 6-month episode of care was developed. Cancer types and proportions of patients treated in the practice were estimated from an OCM report. All-cause healthcare costs were obtained from published literature. It was assumed that if a practice restricts usage of branded TKIs for newly-diagnosed CML patients, 80% of the market share of branded imatinib and 50% of the market shares of 2^nd-gen TKIs would shift to generic imatinib. Among established TKI-treated patients, it was assumed that 80% of the market share of branded imatinib and no patients treated with 2^nd-gen TKIs would shift to the generic.

Results: Four CML patients were estimated for a 1,000-cancer patient OCM practice with a total baseline healthcare cost of $51,345,812 during a 6-month episode. If the practice restricts usage of branded TKIs, the shift from 2^nd-gen TKIs to generic imatinib would reduce costs by $12,970, while shifting from branded to generic imatinib lowers costs by $25,250 during a 6-month episode. Minimum reductions of $3,013,832 in a one-sided risk model and $2,372,010 in a two-sided risk model are required for PBP eligibility; the shift from 2^nd-gen TKIs to generic imatinib would account for 0.4% and 0.5% of the savings required for a PBP, respectively.

Conclusions: This analysis indicates that the potential cost reduction associated with restricting branded TKI usage among CML patients in an OCM setting will represent only a small proportion of the cost reduction needed for PBP eligibility.