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Timing Decision (timing + decision)
Selected AbstractsPredicting effective fungicide doses through observation of leaf emergencePLANT PATHOLOGY, Issue 6 2000N. D. Paveley Experimental data were used to test the hypothesis that the effective fungicide dose (ED) , the dose required to achieve a given level of disease suppression , varies in a predictable manner according to the pattern of development of the wheat canopy. Replicated and randomized field plots received a single systemic fungicide spray at either zero (control), 0·25, 0·5, 0·75 or 1·0 dose (the recommended dose), at one of eight timings from April to June. Wheat cultivars and locations for experiments were selected to promote epidemics of septoria tritici spot and yellow rust caused by Septoria tritici (anamorph of Mycosphaerella graminicola) and Puccinia striiformis, respectively. Logistic or exponential disease progress curves were fitted to disease severity data and used to estimate the date of disease onset (t0) and relative epidemic growth rate (r) on each leaf layer for each treatment. Area under the disease progress curve (AUDPC) values were used to construct fungicide dose by spray timing response surfaces for each of the upper four leaves. A parsimonious function, with an exponential form in the dose,response dimension and a normal distribution in the timing dimension described a high proportion of the variation in AUDPC (R2 values ranging from 0·73 to 0·97). Consistent patterns of treatment effect were noted across pathogen species, leaf layers, sites and seasons. Fungicide applications that coincided with full leaf emergence delayed t0 on that leaf layer. Treatments applied after full leaf emergence did not delay t0, but reduced r. Progressively earlier or later treatments, or lower doses, had decreasing effects. AUDPC was affected more by t0 than r. AUDPC response surface parameter estimates showed that curvature of the dose,response was not affected by spray timing, but appeared to be a characteristic of the fungicide,pathogen combination. However, the lower asymptote of the dose,response curve, and hence the ED, varied substantially with spray timing. The pattern of change in ED with spray timing was consistent across a range of leaf layers, pathosystems and seasons, and the spray timing at which the ED was minimized varied only within a small range, around the time of leaf emergence. In contrast, variation in untreated disease severity, resulting from variation in initial inoculum and weather, was large. It was concluded that the main value of disease forecasting schemes may be in their capacity to predict the level of untreated disease, to which the economic optimum, or ,appropriate', dose relates. Spray timing determines the part of the canopy where disease will be efficiently controlled and hence the green leaf area saved. Timing decisions should relate to observations of emergence of those leaf layers important to yield. [source] Optimal timing of switches between product sales for sports and entertainment ticketsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 1 2008Matthew J. Drake Abstract Like airlines and hotels, sports teams and entertainment venues can benefit from revenue management efforts for their ticket sales. Teams and entertainment venues usually offer bundles of tickets early in their selling horizon and put single-event tickets on sale at a later date; these organizations must determine the best time to offer individual tickets because both types of ticket sales consume the same fixed inventory. We model the optimal a priori timing decision for a seller with a fixed number of identical tickets to switch from selling the tickets as fixed bundles to individual tickets to maximize the revenue realized before the start of the performance season. We assume that bundle and single-ticket customers each arrive according to independent, nonhomogeneous Markovian death processes with a linear death rate that can vary over time and that the benefit from selling a ticket in a package is higher than from selling the ticket individually. We characterize the circumstances in which it is optimal for the seller to practice mixed bundling and when the seller should only sell bundles or individual tickets, and we establish comparative statics for the optimal timing decision for the special case of constant customer arrival rates. We extend our analytical results to find the optimal time for offering two groups of tickets with high and low demand. Finally, we apply the timing model to a data set obtained from the sports industry. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2008 [source] Trend derivatives: Pricing, hedging, and application to executive stock optionsTHE JOURNAL OF FUTURES MARKETS, Issue 2 2007Markus Leippold Both institutional and private investors often have only limited flexibility in timing their investment decision. They look for investments that will ideally be independent of the timing decision. In this article, a new class of derivative products whose payoff is linked to the trend of the underlying instrument is introduced. By linking the trend to the payoff, the timing of the decision becomes less important. Therefore, trend derivatives offer some time-diversification benefits. How trend derivatives are designed and priced is shown. Due to their peculiar features, trend derivatives offer some interesting applications such as executive stock option plans. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:151,186, 2007 [source] The development of taiwan arterial traffic-adaptive signal control system and its field test: A taiwan experienceJOURNAL OF ADVANCED TRANSPORTATION, Issue 4 2009Yueh-Tzu Wu Abstract This Taiwan traffic-adaptive arterial signal control model borrowed its traffic flow framework mainly from a British traffic-adaptive control model with a cyclic traffic progression function, i.e. SCOOT (Split Cycle Office Optimisation Technique). The new arterial control model can take into account delays of both major and minor streets and make real-time signal timing decisions with optimal two-way signal offsets, so as to create the best arterial signal operation performance. It has been developed to be an online real-time software for both simulation testing and field validation. Through simulation, it was found that the performance when operating this newly developed real-time arterial traffic-adaptive model was significantly better than when using the optimal fixed-time arterial timing plan. On the aspect of field testing, three signalized intersections located in East District, Tainan City, Taiwan were selected to be the test sites. Fairly good traffic control performance has been demonstrated in that it can effectively reduce travel delays of the control arterial as a whole. Additional discussions about how to combine travel delay and the total number of vehicle stops into a new control performance index have also been included to make the new traffic-adaptive model more flexible and reasonable to meet the expectations of different driver groups in the arterial system. [source] The impact of firm introductory strategies on consumers' perceptions of future product introductions and purchase decisionsTHE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 2 2001Derrick S. Boonea In this research, we develop and test a model of the consumer's decision to immediately purchase a technologically advanced product or to delay such a purchase until a future generation of the product is released. We propose that for technologically advancing products, consumers consider both performance lag (how far behind am I now) and expected performance gain (how far ahead will I be if I wait to buy a future expected release) in their purchase decisions. Furthermore, we hypothesize that a firm's past product introductory strategy can significantly influence consumer perceptions of performance lag, performance gain, and the rate at which a product is advancing technologically. We also propose that these perceptions of lag, gain and rate of technological change influence purchase action and ultimately determine whether or not a consumer will delay or immediately purchase a firm's current technological offering. We investigate the above relationships by introducing a model of consumer purchase behavior that incorporates the effects of a firm's frequency and pattern of next generation product introduction, and test the impact of different introductory strategies on performance lag, gain, rate of change perceptions, and purchase action. In our first study we test our model in a monopolistic setting and show that, holding all else fixed, infrequent product upgrades and/or increasing intergenerational release times result in consumers perceiving larger performance lags and gains. We also show that, holding all else fixed, consumers with larger performance lags and/or gains are less likely to delay their purchases of the currently best available product. In our second study we test our model in a competitive setting and show that, holding all else fixed, a firm's past pattern of new product introduction can influence consumers' perceptions of the firm's product's rate of technological change. We also find that consumers are more likely to purchase products which they perceive to have higher rates of technological change. The key insight from this research is that firms have a strategic tool at their disposal that has been overlooked,the pattern of introduction of next generation products. Our findings suggest that a change in the frequency and/or pattern of introduction, in and of themselves, can influence consumers' perceptions of future product introductions, and ultimately influence their purchase actions. Specifically, we demonstrate that by better understanding consumers' purchase timing decisions, firms may be able to induce purchase on the basis of introductory frequency and pattern alone. Additionally, we demonstrate that by strategically managing consumer expectations of future product introductions, firms may be able to decrease the purchase likelihoods of competing products. Implications of our research and its application to the pattern and timing of preannouncements for new products are also explored. [source] | ||||||||||