Effect Of Churn Research Articles

Business dynamism and regional growth across the business cycle: Implications for recovery from the COVID‐19 crisis

This paper sheds light on regional recovery prospects from the coronavirus disease 2019 (COVID‐19) crisis by examining the link between gross rates of establishment openings and closures and local economic growth spanning the 2001 recession and the 2007–2009 global financial crisis (GFC). Consistent with existing literature, our results show that US counties with historically higher rates of dynamism – measured here as rates of establishment openings and closures, or churn – experience faster medium‐run employment growth rates. Our novel finding relates to the time‐varying effects of churn. Using a fixed‐effects panel model of US counties from 1998 to 2018, we find higher pre‐recession churn to be associated with larger employment losses during the GFC, and slightly faster employment gains during the subsequent recovery. High‐churn counties experienced slower gains in median household incomes during both the 2001 recession and the GFC, but more rapid decreases in poverty rates during macroeconomic expansions. We conclude by identifying regions with historically low establishment churn that have suffered high employment losses during the COVID‐19 crisis and may be in need of support to aid recovery.

The impact of carceral churn and healthcare organizations on HIV/AIDS incidence in Arkansas

•Penal and healthcare institutions generate and mitigate community-level health inequality, respectively.•Arkansas Counties with high prison churn and disadvantage have higher rates of HIV/AIDS.•Hospital density moderates effect of prison churn on incidence of HIV/AIDS.

Round and Round They Go: The Relationship Between Changing Grades and Schools and Teacher Quality and Absence Rates

Research on teacher churn has produced conflicting conclusions as to its impact on students and teachers. We bring clarity to this work by combining and expanding on analytical approaches used in earlier research to determine how and when different types of churn (i.e., grade, school) impact teacher effectiveness and attendance. Using data from the Los Angeles Unified School District, our results suggest differences based on analytical approach but ultimately show that changing schools and grades may be less of an issue than previously reported. In addition, in the case of school churn, a beneficial match in their new school sites may matter more for teacher outcomes than potential disruptive effects of churn. We conclude with implications for policy and future research.

Systematic Evaluation of LibreSocial—A Peer-to-Peer Framework for Online Social Networks

Peer-to-peer (P2P) networks have been under investigation for several years now, with many novel mechanisms proposed as is shown by available articles. Much of the research focused on showing how the proposed mechanism improves system performance. In addition, several applications were proposed to harness the benefits of the P2P networks. Of these applications, online social networks (OSNs) raised much interest particularly because of the scalability and privacy concerns with centralized OSNs, hence several proposals are in existence. However, accompanying studies on the overall performance of the P2P network under the weight of the OSN applications outside simulations are very few, if any. In this paper, the aim is to undertake a systematic evaluation of the performance of a P2P framework for online social networks called LibreSocial. Benchmark tests are designed, taking into account the random behavior of users, effects of churn on system stability and effect of replication factor. We manage to run benchmark tests for up to 2000 nodes and show the performance against costs of the system in general. From the results it is evident that LibreSocial’s performance is capable of meeting the needs of users.

Retail store churn and performance – The moderating role of sales amplitude and unpredictability

One of the key decision making processes for retailer performance is optimizing store locations which involves both the opening and closing of stores, or store churn. With the recent challenges in the retail industry illustrated by failing retailers and massive store closures, the discussion of the value or detriment of store churn is at the forefront, yet limited studies shed light on this important aspect of retail performance. Drawing on Dynamic Decision Making framework, using a longitudinal sample we investigate whether store churn generates negative or positive returns and if two environmental factors relevant to the retail industry—amplitude and unpredictability of seasonally adjusted industry quarterly sales—influence the relationship between store churn and performance. In a sample of 115 publicly traded retail chains in the US between the first quarter of 1986 to the first quarter of 2017, we found that store churn has a positive but small overall effect on performance and that under conditions of lower levels of amplitude or low unpredictability of industry sales, the small direct effect of store churn becomes a much greater positive effect. The findings show that, amongst a mature population of retailers, store churn in the face of lower amplitude and unpredictability may lead to higher returns.

Effect of Friends’ Churn on Consumer Behavior in Mobile Networks

We study how consumers decide which tariff plan to choose and whether to churn when their friends churn in the mobile industry. We develop a theoretical model showing conditions under which users remain with their carrier and conditions under which they churn when their friends do. We then use a large and rich anonymized longitudinal panel of call detailed records to characterize the consumers’ path to death with unprecedented level of detail. We explore the structure of the network inferred from these data to derive instruments for friends’ churn, which is typically endogenous in network settings. This allows us to econometrically identify the effect of peer influence in our setting. On average, we find that each additional friend that churns increases the monthly churn rate by 0.06 percent. The observed monthly churn rate across our dataset is 2.15 percent. We also find that firms introducing the pre-paid tariff plans that charge the same price to call users inside and outside the carrier help retain consumers that would otherwise churn. In our setting, without this tariff plan the monthly churn rate could have been as high as 8.09 percent. We perform a number of robustness checks, in particular to how we define friends in the social graph, and show that our results remain unchanged. Our paper shows that the traditional definition of customer lifetime value underestimates the value of consumers and, in particular, that of consumers with more friends due to the effect of contagious churn and, therefore, managers should actively take into account the structure of the social network when prioritizing whom to target during retention campaigns.

A novel collection optimisation solution maximising long-term profits: a case study in an international bank

When customers fail to pay the amount they owe to their bank related with a credit product (credit cards, overdraft accounts or instalment loans), the bank starts the collection process. This process typically lasts for a particular amount of time after which the customer is labelled as defaulted and a litigation period is launched. Banks try to minimise the percentage of credit exposure that goes to litigation since it negatively affects the bank’s profitability. Accordingly, they take various actions to maximise the collections before litigation. In this study, we approach this problem from a different perspective as we maximise not the short-term collections but the long-term revenues from customers by incorporating the churn effects of these actions in our modelling.

Estimating the impact of interacting with sales representatives on customer-specific revenue and churn behavior

This paper uses transaction-level data from a firm in the High Technology sector to compare the revenue garnered from customers who purchase via sales representatives to that garnered from customers who purchase online. The interaction mode may be correlated with the customer’s unobserved valuation for the service, and this potential endogeneity is addressed using an instrumental variable. Specifically, the data indicate whether the customer’s details were recorded in the company’s information systems following an initial contact, such as the download of a free version from the company’s website. The availability of such leads facilitated representatives’ ability to contact customers, generating exogenous variation in the probability of interacting with a representative. Instrumental variable estimates indicate that such interaction lowers the total revenue garnered from a paying customer during the sample period. The primary driver of this result is a churn effect: customers who purchased online displayed a longer overall relationship with the firm, and were more likely to renew an expiring subscription. An alternative explanation, according to which representatives lowered revenues by reassuring customers regarding the adequacy of cheaper versions of the product, is not supported by the data.

Evaluation of hierarchical DHTs to mitigate churn effects in mobile networks

Existing flat peer-to-peer (P2P) systems based on distributed hash tables (DHTs) perform unsatisfactorily under churn due to their non-hierarchical topology. These flat DHTs (FDHTs) experience low lookup success ratio, high lookup latency and high bandwidth usage as a consequence of the presence of churn. With this, we explore the use of hierarchical DHT (HDHT), specifically the superpeer design, in mitigating the effects of churn. To the best of our knowledge, we are the first to intensively examine HDHTs with and without high churn through simulations.Using the OMNeT++ simulator and the OverSim framework, we analyze flat and hierarchical DHTs with and without churn. Results show that the implemented HDHTs perform more satisfactorily than a flat DHT because of better fault isolation and smaller cluster sizes at the cost of higher superpeer traffic. HDHTs are more stable as they have better lookup success ratios. They are more efficient as evidenced by lower lookup latencies and lower average node bandwidth usage. They are more scalable since their performance do not degrade significantly even at high population. With this, the implemented HDHTs can be utilized to alleviate the effects of churn in mobile networks.

Achieving maximum utilization of peer’s upload capacity in p2p networks using SVC

We propose an algorithm that exploits the properties of Scalable Video Coding (SVC) in order to minimize the upload bandwidth at each peer. More specifically, we propose streaming different layers of the same video from different peers. The paper defines an optimization problem to handle the upload bandwidth at each peer. However, the solution to the proposed problem is NP complete. Therefore, we propose an approximation algorithm to solve this problem. In addition, seed servers are introduced in order to deal with extra load in the network. The proposed method provides better performance as compared to the current approaches that use single layer video in combination with SVC. We have compared our simulation results with the model proposed in Shabnam and Mohamed (2010). The simulation results show that the proposed model improves diversity, increases average video quality, reduces the effect of churn and manages flash crowds.

Technological change in the U.S. music industry: Within-product, cross-product and churn effects between competing blockbusters

In this paper, we develop a new innovation diffusion model for two competing products, which allows us to evaluate the effect of competition both on the dynamics of within-product and cross-product word-of-mouth and on the definition of the residual market potential of each product. This model, which we call Lotka–Volterra model with churn, LVch, generalizes another model for competition, the unbalanced competition and regime change diachronic model (UCRCD), which assumes a common residual market and a delayed entrance for the second product. We compare the performance of these models in describing the competition between two blockbuster formats in the music industry, the compact cassette and the compact disc. In particular, we analyze the evolution of these technologies in the U.S. market for pre-recorded music, for which annual sales data are available from 1973 to 2012, and find that the LVch model outperforms the UCRCD. An interesting aspect of this application relies on the fact that there is a single product, the music album, which is commercialized in two different formats, so that competition arises between formats and not between two products in the same commercial category.

A novel replication technique to attenuate churn effects

Dealing with the churn problem is an important requirement in distributed systems in general and more precisely in structured peer-to-peer overlay networks due to their dynamicity. This problem refers to the change in the set of participating nodes due to the frequent joins, leaves or failures. Such variations induce at worst the loss of objects and at least performance degradation. This is due to the reorganization of the set of replicas of the affected objects. Till now, this problem has been mostly addressed at the p2p routing level to ensure the reach ability of peers by maintaining the consistency of the logical neighbors. However, the main challenge for structured p2p systems is to protect the ability of the system to locate any present object. At the storage level, avoiding data losses is still an issue when a reconfiguration of the participant peers occurs. In this paper and after presenting first the existing replication techniques, we propose the zone replication technique used in both Chord and Kademlia protocols in order to attenuate churn effects. Finally, we point out some ways that can lead to better and maybe robust replication protocols.

A Defense Model of Reactive Worms Based on Dynamic Time

The popularity of reactive worms, whose attacking behavior inherits characteristics from both active worms and passive worms, has brought great threat to P2P networks in recent years. Most existing defense models only focus on the effects of P2P churn on reactive worm's propagation, but neglect the impact of user behaviors on the spread of worms. This paper proposes a defense model of reactive worms based on dynamic time with full consideration of various dynamic factors that restrict the propagation of reactive worms in real networks; then compares major distinctions of several key parameters in worms' propagation between models based on mean-field theory and the presented dynamic-time-based one; and deduces the crucial periods of time within a particular 24-hour day for defending against reactive worms' attack. Eventually simulation experiment shows this defense model is feasible and effective.

The Effect of Churn on “Community Viral Load” in a Well-Defined Regional Population

The concept of community viral load (CVL) was introduced to quantify the pool of transmissible HIV within a community and to monitor the potential impact of highly active antiretroviral therapy (HAART) on reducing new infections. The implications of churn (patient movement in/out of care in a community) on CVL have not been studied. The annual CVL was determined in the entire geographic HIV population receiving care in southern Alberta from 2001 to 2010; the CVL for specific subpopulations was analyzed for 2009. CVL was determined for patients under continuous care, newly diagnosed, new to the region, moved away, returned, and lost to follow-up (LTFU). Viral loads (VLs) <50 or <200 copies per milliliter were deemed undetectable and suppressed, respectively. The mean VL per patient and total VL were used to determine CVL. From 2001 to 2010, the HAART uptake for all patients increased from 62% to 81%, undetectability from 32% to 66%, and suppression from 49% to 72%. The annual total CVL however did not vary significantly after 2003. Incidence rates for new locally diagnosed infections increased from 4.4 to 5.8/100,000 per year. In 2009, newly diagnosed HIV patients (6.6%) contributed 37.5% to the CVL, whereas patients transferring in/out of the region or lost to follow-up contributed 33% to the CVL. Patients in continuous care (79% of all patients) contributed 29.5% to the total CVL. Increasing HAART coverage did not reduce the CVL or reduce new HIV diagnoses in our population. The effect of churn significantly limited CVL use as a measure for evaluating the impact of HAART in reducing HIV transmissions in our population.

A video distribution game with enhanced quality of experience for wireless networks

Video communication over unpredictable wireless medium is a challenging research area. Many mathematical solutions have been proposed by researchers for high-quality video forwarding over such networks. An important example is the game theory. The non-cooperative game theory can be adopted to represent the selfish behaviour of network users. In the current study, a non-cooperative quality game framework (QGF) has been introduced, in which by exploiting a related quality metric, scalable video users try to enhance their perceived quality in a distributed manner in mobile ad-hoc networks. The behaviour of the Nash equilibrium point has been analysed and a distributed resource allocation strategy has been introduced. Also, the quality properties of the proposed QGF under the user churn effects have been investigated. The assigned rates in the quality game can be considered as rate-feedbacks for on-line rate adaptation of a moderate scalable video encoder such as HEVC, H.264/MPEG4 AVC etc. Some experimental results have been presented to validate the theoretical results.

Understanding the impact of churn in dynamic oligopoly markets

We incorporate the effects of churn, which refers to customers switching to competing brands, in a dynamic model of advertising for oligopoly markets. Each firm’s market share depends not only on its own and competitors’ advertising decisions, but also on market churn. Applying differential game theory, we derive a feedback Nash equilibrium under symmetric and asymmetric competition. We obtain explicit solutions and discover the counter-intuitive result that, as market churn increases, firms should decrease advertising rather than increase it to counteract the impact of churn.

RelaxDHT

DHT-based P2P systems provide a fault-tolerant and scalable means to store data blocks in a fully distributed way. Unfortunately, recent studies have shown that if connection/disconnection frequency is too high, data blocks may be lost. This is true for most of the current DHT-based systems' implementations. To deal with this problem, it is necessary to build more efficient replication and maintenance mechanisms. In this article, we study the effect of churn on PAST, an existing DHT-based P2P system. We then propose solutions to enhance churn tolerance and evaluate them through discrete event simulation.

Impact of Churn on Object Management Policies Deployed in CDN-P2P Systems

In this paper, we study the impact of churn on object management policies deployed in a CDN-P2P system. The effectiveness of buffer enlargement and replicating control, in reducing the effects of churn on these policies, is analyzed. We have found that neither the simply enlargement of peers' storage capacity nor a zero replicating strategy are effective actions to improve performance of an object management policy. Policies that implements different caching strategies are evaluated, and a YouTube video collection, which records over 1.6 million video's log, is used in our experimental studies

Effect of node churn on frame interval for peer-to-peer video streaming with data-block synchronization mechanism

Coolstreaming is a mesh based peer-to-peer (P2P) video streaming system in which single video stream is decomposed into multiple sub-streams. A client-peer node retrieves the sub-streams from multiple parent-peer nodes, combining them into the original video stream. Each client-peer node has two buffers, a synchronization buffer and a cache buffer, and arriving data blocks are synchronized at the synchronization buffer and then forwarded to the cache buffer. In this buffering system, data-block synchronization is important to guarantee high video quality. In this paper, we consider the effect of churn on the performance of data-block synchronization scheme with which data blocks are simultaneously forwarded just after all the data blocks composing a macro data block arrive at the synchronization buffer. It is assumed that data blocks belonging to a sub-stream arrive at the client-peer node according to an interrupted Poisson process. The synchronization buffer is modeled as a multiple-buffer queueing system with homogeneous interrupted Poisson processes, and the mean forwarding interval is derived. Numerical examples show that the average forwarding interval increases as parent-peer nodes leave more frequently.

Understanding the Impact of Churn in Dynamic Oligopoly Markets

We incorporate the effects of churn, which refers to customers switching to competing brands, in a dynamic model of advertising for oligopoly markets. Each firm’s market share depends not only on own and competitors’ advertising decisions, but also on market churn. Applying differential game theory, we derive a feedback Nash equilibrium under symmetric and asymmetric competition. We obtain explicit solutions and discover the counter-intuitive result that, as market churn increases, firms should decrease advertising rather than increase it to counteract the impact of churn.