Some contributions to modeling usage sensitive warranty servicing strategies and their analyses

Providing a warranty as a part of a product\u27s sale is a common practice in industry. Parameters of such warranties (e.g., its duration limits, intensity of use) must be carefully specified to ensure their financial viability. A great deal of effort has been accordingly devoted in attempts to reduce the costs of warranties via appropriately designed strategies to service them. many such strategies, that aim to reduce the total expected costs of the warrantor or / and are appealing in other ways such as being more pragmatic to implement - have been suggested in the literature. Design, analysis and optimization of such servicing strategies is thus a topic of great research interest in many fields. In this dissertation, several warranty servicing strategies in two-dimensional warranty regimes, typically defined by a rectangle in the age-usage plane, have been proposed, analyzed and numerically illustrated. Two different approaches of modeling such usage sensitive warranty strategies are considered in the spirit of Jack, Iskandar and Murthy (2009) and Iskandar (2005). An `Accelerated Failure Time\u27 (AFT) formulation is employed to model product degradation resulting due to excessive usage rate of consumers. The focus of this research is on the analysis of warranty costs borne by the manufacturer (or seller or third party warranty providers) subject to various factors such as product\u27s sale price, consumer\u27s usage rate, types and costs of repair actions. By taking into account the impact of the rate of use of an item on its lifetime, a central focus of our research is on warranty cost models that are sensitive to the usage rate. Specifically, except the model in Chapter 4 where the rate at which an item is used is considered to be a random variable; all other warranty servicing policies that we consider, have usage rate as a fixed parameter, and hence are policies conditional on the rate of use. Such an approach allows us to examine the impact of a consumer\u27s usage rate on the expected warranty costs. For the purpose of designing warranties, exploring such sensitivity analysis may in fact suggest putting an upper limit on the rate of use within the warranty contract, as for example in case of new or leased vehicle warranties. A Bayesian approach of modeling 2-D Pro-rated warranty (PRW) with preventive maintenance is considered and explored in the spirit of Huang and Fang (2008). A decision regarding the optimal PRW proportion (paid by the manufacturer to repair failed item) and optimal warranty period that maximizes the expected profit of the rm under different usage rates of the consumers is explored in this research. A Bayesian updating process used in this context combines expert opinions with market data to improve the accuracy of the parameter estimates. The expected profit model investigated here captures the impact of juggling decision variables of 2-D pro-rated warranty and investigates the sensitivity of the total expected profit to the extent of mis-specification in prior information

Long-term safety of glycopyrrolate: A randomized study in patients with moderate-to-severe COPD (GEM3)

AbstractBackgroundChronic obstructive pulmonary disease (COPD) is one of the leading causes of death in the United States. Long-acting muscarinic antagonists (LAMAs) are a class of medications used as maintenance therapy for COPD. The GEM3 (Glycopyrrolate Effect on syMptoms and lung function) study assessed the long-term safety and efficacy of a LAMA, glycopyrrolate (GLY) 15.6 μg twice daily (b.i.d.), compared with an approved long-acting β2-agonist (LABA), indacaterol (IND) 75 μg once daily (q.d.) in patients with stable, symptomatic COPD with moderate-to-severe airflow limitation.MethodsThis 52-week, multicenter, double-blind, parallel-group study randomized patients (1:1) of the United States to receive GLY 15.6 μg b.i.d. or IND 75 μg q.d. both delivered via the Neohaler® device. The primary objective was to assess the safety and tolerability in terms of adverse event (AE) reporting rates over 52 weeks. Safety was also determined by evaluating multiple secondary endpoints, including vital signs, electrocardiograms (ECGs), and time to first moderate or severe exacerbation. Efficacy-related secondary endpoints included pre-dose forced expiratory volume in one second (FEV1) and forced vital capacity (FVC).ResultsOf the 511 randomized patients (GLY, n = 254; IND, n = 257), 81.6% completed the study. The overall incidences of AEs (GLY, 77.3%; IND, 77.0%) and serious AEs (GLY, 13.1%; IND, 13.3%) were comparable between the groups. The incidence of major adverse cardiovascular events was low and comparable between the groups. No clinically relevant differences for vital signs or ECG parameters were observed between the treatment groups. The three sudden deaths reported within 30 days of the treatment (GLY, n = 2; IND, n = 1) were adjudicated as unrelated to the study medication. In terms of efficacy, GLY 15.6 μg b.i.d. showed improvements in pre-dose FEV1 and FVC from baseline, which was comparable to those with IND 75 μg q.d., with no statistically significant differences. No significant differences were observed between the treatment groups in the time to first moderate or severe COPD exacerbation.ConclusionGLY 15.6 μg b.i.d. showed a long-term safety profile comparable to that of IND 75 μg q.d. and provided rapid and sustained bronchodilation over 52 weeks in patients with COPD with moderate-to-severe airflow limitation.Clinical trial registration numberNCT01697696