The impact of review sentiments on occupancy: Evidence for signalling theory from peer-to-peer accommodation

Using data from 16,144 peer-to-peer properties in London, we study the impact of the two components of user-generated content – rating and sentiment – on occupancy rate. Our methodology is innovative because, firstly, we control for price variation when estimating these review-occupancy effects and secondly, we estimate interaction and curvilinear effects. We find that sentiment and rating have significant positive effects on occupancy rate; there is some evidence that sentiment and rating interact, one reinforcing the other; for a typical property among those analysed, an outstanding review increases occupancy by a fifth in relative terms. Thus, we interpret these associations as evidence that rating and sentiment signal value, and we estimate the strength of the signal in the peer-to-peer accommodation sector

The binomial-match, outcome uncertainty, and the case of netball

We introduce the binomial-match as a model for the bivariate score in a paired-contest. This model is naturally associated with sports in which the restart alternates following a goal. The model is a challenger to the Poisson-match, a pair of independent Poisson random variables whose means are related to the strengths of the competing teams. We use the binomial-match primarily to study the relationship between outcome uncertainty and scoring-rate, particularly for high values of the scoring-rate. Netball has a high scoring-rate and motivates our model development. In the binomial-match framework, we also evaluate rule-variations, and study tactical play in netball. Our analysis suggests that the binomial-match is not a better forecaster than the Poisson-match, but it is better for representing outcome uncertainty and evaluating rule-variations and tactics. In general, we find that the binomial-match implies greater outcome uncertainty than the Poisson match, for a given scoring-rate, and that an alternating-restart is a good rule for reducing the frequency of tied outcomes. For netball in particular, we show that starting the final quarter with possession in a close, balanced match may confer a significant advantage

A hybrid maintenance policy with fixed periodic structure and opportunistic replacement

We model a maintenance policy with fixed periodic structure that is a hybrid of periodic inspection and opportunistic replacement. The policy is applicable to geographically remote systems such as offshore wind farms. The policy has three phases. Initially, there is an inspection phase to identify early defects. This is followed by a wear out phase during which corrective replacements are performed. Preventive replacement occurs at the end of this phase. The novelty of the model is an opportunistic phase, which overlaps with the latter part of the corrective phase, when preventive replacement is executed early if an opportunity arises. In this way, we model the reality in which remote systems with high logistics costs and restricted access may benefit from opportunistic visits for maintenance. Using a numerical example, we analyse the behaviour of the decision variables for a range of values of the parameters common to such systems. These parameters relate to: component heterogeneity; restricted access; default (failure to execute a planned action); arrival of opportunities and other standard parameters in a maintenance cost model. Specifically, our results indicate when opportunities can have a significant impact on the cost-rate of the optimum policy, but that leveraging opportunities cannot achieve a very high availability. Generally, we demonstrate that maintenance planning should be flexible when factors beyond the control of the maintainer impact maintenance effectiveness

Joint maintenance and spare-parts inventory models: a review and discussion of practical stock-keeping rules

It is natural to coordinate spare-parts inventory planning and maintenance. However, work in the former area often neglects part utilisation, and work in the latter the fact that effective execution of maintenance schedules is conditioned to the availability of the necessary spare parts. This paper is a call for further integration between the two areas, and to that end we review the literature on mathematical modelling and analysis of inventory-maintenance-planning. We are not the first to address this issue (though we take a fresh perspective to the problem), but we are the first to complement such review with a discussion of simple stock keeping rules that may be used effectively in practice. We identify a growing gap between modelling and application, between theory and practice, that justifies the presentation of these simple stock keeping rules for the joint planning of inventory and maintenance. Thus, our work should be of interest not only to researchers who are looking for promising avenues for future research, but also to practitioners who are seeking to improve inventory-maintenance operations

Condition-based maintenance for a two-component system with dependencies

International audienceThe paper deals with a condition-based maintenance policy for a two-component system with dependencies. Two kinds of dependency are investigated. The first is state dependence whereby the deterioration speed of each component depends not only on its own state (deterioration level) but also on the state of the other. The second is economic dependence whereby combining maintenance activities is cheaper than performing maintenance on components separately. To select a component/group of components to be preventively maintained, adaptive preventive maintenance and opportunistic maintenance rules are proposed. A cost model is developed to find the optimal value of decision parameters. A numerical example is introduced to illustrate the use and the advantages of the proposed approach in the maintenance optimization framework

Mathematical modelling of mission-abort policies: a review

This paper reviews works that consider the mathematical modelling of mission-abort policies. In a mission-abort policy (MAP), a valuable, and perhaps vulnerable system performs a mission with two, sometimes conflicting objectives, mission success and system survival, and the purpose of modelling is to determine conditions under which a mission should be aborted. Such problems are important in defence, and emerging in transportation and health management. We classify models by: the nature of the mission and the system; the nature of the return or rescue; type of deterioration model; and the decision objectives. We show that the majority of works consider a model of a one system, one target mission in which the mission is aborted once the hazard of failure reaches a critical level and the operating environment is the same for the outbound and inbound parts of the mission. Typically, the hazard of failure depends on the number of shocks received so far. Our analysis indicates that there has been little modelling development for multiple systems that can multi-task and dependent systems with common-cause failures, for example. We find no evidence that MAPs are used in practice and no works reviewed develop software demonstrators. We think there is considerable scope for modelling applications in transportation (e.g. dynamic train re-scheduling, last-mile logistics) and medical treatments, and MAPs may be more general than the literature that we have reviewed suggests