O presente estudo tem como principal objetivo avaliar o impacto de aspectos contingenciais no modelo básico do efeito da espera na avaliação geral de um serviço. Com base em estudos referentes à espera já realizados, o presente trabalho definiu o “modelo básico do efeito da espera na avaliação geral do serviço” que consiste no impacto negativo da espera na avaliação geral do serviço por meio da suscitação de emoções negativas. A influência de fatores contingenciais sobre o modelo é a principal contribuição do estudo, dado que essa abordagem não havia sido ainda estudada. Inicialmente, foi realizada uma etapa exploratória, qualitativa, para investigar as relações propostas no modelo teórico, assim como para compreender melhor os serviços de saúde, campo de estudo da pesquisa. Na sequência, a influência do envolvimento do consumidor, da singularidade do serviço, da pressão do tempo e do relacionamento interpessoal no modelo central foi investigada através da realização de uma survey com 382 pacientes As hipóteses foram testadas por meio de modelagem de equações estruturais, com o software LISREL 8.51. Os resultados indicam que o envolvimento do consumidor tem impacto positivo no seu tempo de espera aceitável. Já o efeito da singularidade do serviço sobre essa mesma variável não foi confirmado. A pressão do tempo apresentou impacto positivo no tempo de espera percebido e o efeito moderador do relacionamento interpessoal na relação entre as respostas afetivas negativas e a avaliação geral do serviço também foi confirmada. Além das hipóteses propostas, foi realizado um teste exploratório segundo o qual se confirmou o efeito moderador da variável gravidade sobre as relações que compõe o modelo básico do efeito da espera da avaliação geral do serviço. No final, os resultados são discutidos, e as limitações do estudo e sugestões para futuras pesquisas são apresentadas. / The most important objective of the present study is to evaluate the impact of the contingency aspects on the basic model of the waiting effect in the overall service evaluation. Based on studies in reference to the wait already carried out, this study defined the "basic model of the waiting effect on the general evaluation of the service" as being the negative impact of waiting in the general evaluation of the service because of the rise of negative emotions. The influence of contingency factors over the model is the most important contribution of the study as this approach has never been studied before. Iniatially, there was a qualitative exploratory to investigate the proposed relations in the theoretical model, as well as to have a better understanding of health care services, the field study of the research. Following that, the influence of the consumer involvement, the uniqueness of the service, the time pressure and the interpersonal relationship in the central model was investigated through a survey conducted among 382 patients The hypotheses were tested using structural equation modeling with LISREL 8.51 software. The results showed that the consumer involvement have a positive impact in the acceptable waiting time. On the other hand the effect of the uniqueness of the service over the same variable was not confirmed. The time pressure indicated a positive impact on the perceived waiting time and the moderate effect of the interpersonal relationship of the connection between negative affective reactions and the overall service evaluation was also confirmed. Beyond the proposed hypotheses, it was performed a exploratory test whereby it was confirmed the moderator effect of the gravity variable on the relations that form the basic model of the waiting effect on the overall service evaluation. In the end the results are discussed, and the limitations of the study and suggestions for future surveys are presented.

There has been an enormous growth in the Internet usage in recent years, fueled by the increasing number of multimedia applications and widespread availability of World Wide Web (WWW). The end-user generally accesses these applications through web browsing activities. These time-critical services often suffer from the delays ranging from small chunks to long peaks which can have severe implications on the Quality of Experience (QoE). Hence, it is worthwhile to identify the impact of different variations of delay on the end-user QoE. This research focused on the end-user QoE for three different distributions of delays occurring during an e-commerce shopping experiment. By keeping the overall waiting time of every sessions same, the study shows that the end-user QoE is different for different variety of delays. And the research also concludes that, the users prefer small frequently occurring delays as compared to the long rarely occurring delays within a task-driven web browsing session.

Magister Public Health - MPH / The development and provision of equitable and acceptable standard of health services to all segments of the population has been the major objective of the 1993 Ethiopian National health policy. However, community based studies on satisfaction with public health care facilities reveal that the majority of the population are not satisfied with the services provided predominantly as a result of the long waiting times. Studies done on private health facilities on the contrary reveal that patients are satisfied with the service delivered within short waiting times in these clinics. Even though the speculated waiting time is thought to be long among the public health care facilities and short in private clinics, the actual waiting and service times have not been measured and compared. Aim: To determine the waiting and service times among the public and private health care facilities and measure the perceptions of 'acceptable' waiting time among the providers and clients. Materials and methods: A cross sectional observational study using quantitative techniques was carried out amongst patients and staff at selected public and private health care facilities in Gondar District. Stratified sampling method was used to select facilities. All patients visiting the selected facilities and all staff who provided service to patients on the day of the study were included in the time-delimited sample. Data was collected by research assistants and health workers from all patients attending the health care facility by registering the arrival and departure time of each patient to the facility and to each service point on a patient flow card. Then data was cleaned and captured by a specific Waiting and Service Time database. Descriptive statistics was done on waiting and service times for each facility and this was summarized for each public and private health facility by using tables and graphs. Finally a comparison was made for private and public health facilities by using Wilcoxon-mann-whitney non parametric tests. / South Africa

Magister Public Health - MPH / Aim: To determine the waiting and service times among the public and private health care facilities and measure the perceptions of “acceptable” waiting time among the providers and clients.

(i) The thesis sets out to address the problematic phenomenon of Systems of Congestion via Basic Queueing Theory. The theory, and its application in practice, appears to be a field of study which is the common domain of “theorists” and “practitioners”. (ii) This professional dichotomy has come about due to diverging interests in that one group is mainly interested in the purity of mathematical modelling, and the other group is motivated to use modelling, which conveniently employs applications oriented solutions. (iii) The schism between the groups has been accentuated by the “practitioners” who in addition to having an interest in steady state system behaviour make use of methods of modelling of the transient operation of complex Systems of Congestion. (iv) At the outset the thesis demonstrates how closed form solutions are obtained for steady state and transient state operation of a selection of Systems of Congestion. The attendant mathematical derivations are elegant and intricate. (v) Having revealed the limited utility of closed-form solutions the thesis proceeds to investigate the feasibility of using dynamical systems theory to study the transient behaviour of complex Systems of Congestion. (vi) The creation of Chaos Theory in recent decades suggests that it may be employed as a useful tool in analysing Systems of Congestion. Iterative Chaos Theory methods of orbit generation for complete Systems of Congestion are therefore examined. The use of such orbit generation methods is found to be satisfactory for simple Systems of Congestion. More than a perfunctory knowledge of chaos mapping is however required. The simplicity of modelling is emphasized. (vii) Based on the results of benchmarking the creation of dynamic system orbits against an existing simulation method, the research advances to modelling of the transient operation of complex systems. Once again the iterative method of orbit generation displays the ease of modelling while simultaneously unfolding system dynamics graphically. (viii) One may hopefully contend that a tool of eminent utility has been developed to aid practitioners in studying and optimizing Systems of Congestion. / Thesis (PhD (Industrial Engineering))--University of Pretoria, 2006. / Industrial and Systems Engineering / Unrestricted

In seismology, an important goal is to attain a better understanding of the earthquake process. In this study of the physics of aftershock generation, I couple statistical analysis with modelling of physical processes in the postseismic period. I present a theoretical formulation for the distribution of interevent times for aftershock sequences obeying the empirically well established Omori law. As opposed to claims by other authors, this work demonstrates that the duration of the time interval between two successive earthquakes cannot be used to identify whether or not they belong to the same aftershock sequence or occur as a result of the same underlying process. This implies that a proper understanding of earthquake interevent time distributions is necessary before conclusions regarding the physics of the earthquake process are drawn. In a discussion of self-organised criticality (SOC) in relation to empirical laws in seismology, I find that Omori's law for aftershocks cannot be used as evidence for the theory of SOC. Instead, I consider that the occurrence of aftershocks in accordance with Omori's law is a result of a physical process that can be modelled and understood. I analyse characteristic features in the spatiotemporal distribution of aftershocks in the south Iceland seismic zone, following the two M6.5 June 2000 earthquakes and a M4.5 earthquake in September, 1999. These features include an initially constant aftershock rate, whose duration is larger following a larger main shock, and a subsequent power law decay that is interrupted by distinct and temporary deviations in terms of rate increases and decreases. Based on pore pressure diffusion modelling, I interpret these features in terms of main shock initiated diffusion processes. I conclude that thorough data analysis and physics-based modelling are essential components in attempts to improve our understanding of processes governing the occurrence of earthquakes.

<p>U doktorskoj disertaciji rešavaju se sledeći problemi: problem opisivanja sistema masovnog opsluživanja kada teorija masovnog opsluživanja nailazi na ograničenja primene, problem predviđanja vremena čekanja, problem modelovanja odnosa na tržištu ekspres usluga kao izvora uticaja na redove čekanja, problem upravljanja brojem aktivnih kanala sistema masovnog opsluživanja i problem uticaja na subjektivno vreme čekanja. Primenom elemenata veštačke inteligencije i statističkih metoda razvijen je model za predviđanje parametra vremena čekanja u realnom vremenu pri jedinicama poštanske mreže za pružanje usluga korisnicima.</p> / <p>The dissertation provides answers to the following issues: the problem of describing the queueing system when the queueing theory encounters limitations in its use, predicting the waiting time, the problem of modeling relations in the market of express services as a source of influence on the queues, managing the number of active channels in the queueing systems and the impact on subjective waiting time. Through application of artificial intelligence and statistical methods, a model has been developed which in real time predicts the parameters of waiting time at the units of postal network that provide service to customers.</p>

O modelo de fila M/M/n+G pode ser usado para descrever o comportamento de uma Central de Atendimento. Nesse modelo as chegadas são Poisson com taxa lambda, o atendimento é exponencialmente distribuído com taxa mi, há n atendentes e os tempos de paciência dos clientes têm distribuição geral. A espera do usuário em fila não pode ultrapassar um tempo (paciência) que tem distribuição G e, se isto ocorrer, ele abandona o sistema. Mandelbaum e Zeltyn [2004] mostraram que existe uma relação linear entre o tempo médio de permanência na fila e a probabilidade de abandono nesses modelos quando a paciência é exponencialmente distribuída. No presente trabalho, estudamos essa relação no caso de distribuiçãao de paciência do tipo mista (com partes discreta e contínua), em que buscamos representar a reação dos usuários às mensagens gravadas reproduzidas periodicamente para aqueles que estão esperando atendimento. Utilizamos duas distribuições de paciência: Exponencial Mista e Uniforme Mista e percebemos que não há uma relação linear entre o tempo médio de espera na fila e a probabilidade de abandono. Observamos que para uma mesma taxa de chegada, o tempo médio de espera na fila é menor para a distribuição de paciência mista quando comparada com a Exponencial ou Uniforme de mesmos parâmetros. Analisamos o que ocorre com essa relação quando alteramos a distribuição do atendimento e percebemos que ela é mais afetada pela média e pelo coeficiente de variação do que pela particular distribuição escolhida para o tempo de serviço. / The M/M/n+G queueing model can be used to describe the behavior of a Call Center. This model has Poisson arrivals with rate lambda, service times are exponentially distributed with rate mi, n agents and the client´s patience time has general distribution. The waiting in line could not exceed a time (patience) which has distribution G, and if it occurs, the client leaves the system. In this models, Mandelbaum and Zeltyn [2004] showed that there is a linear relationship between average waiting time in queue and the probability of abandonment if the distribution of patience is Exponencial. In this work, we study this relationship in the case of patience with mixed distribution (which has discret and continuous parts). Through mixed distributions we try to represent the user´s reaction to recorded messages reproduced periodically when they are waiting for service. We have used Mixed Exponencial and Mixed Uniform distributions and, in both of them, there is not a linear relationship between average waiting time in queue and the probability of abandonment. We observe that for the same arrival rate, the average waiting time in line for mixed distribution is smaller than Exponencial or Uniform distributions with the same parameters. Also, we study the effect on waiting time and abandonment of different distributions of service and we observe that it is more affected by the coeficient of variation and average that by the particular distribution chosen for service.

Made available in DSpace on 2016-04-25T16:44:37Z (GMT). No. of bitstreams: 1 Leandro Ortigoza Martins.pdf: 2024505 bytes, checksum: 84de1edbfa0bb3e9b74e0df2d49c6cdb (MD5) Previous issue date: 2013-11-07 / The diagnostic medical services are perishable and the demand is variable. These are characteristics that struggle the maximization of results. Service providers traditionally offer exams through a scheduling system without overcoming, however, the inefficiency provoked by clients no-show. This study aims at investigating consumer satisfaction levels of the diagnostic medical services in relation to the operational model of scheduling, the acceptance to a new model with no scheduling need (free on demand) and analyzing three secondary dimensions common to the two models. The literature review embraced the historical evolution of the diagnostic medical services in Brazil, as well as the processes, opportunities and challenges associated with said development. It was verified that the existing relationship between perishability and seasonality jeopardizes company profitability due to the fact that it hinders a better use of the installed capacity, dilution of expenses and return on investment. The stage relative to the evolution of services and relationship marketing evidenced the importance of carrying out a survey with the own users of the services. Such research has a quantitative approach with a descriptive exploratory outline, and it was performed in 2.545 customers of a private company of diagnostic medical services in 2013. The data collection took place by applying a questionnaire and the following statistics techniques were adopted to assess the results: average comparisons, relationship between categorical variables (&#967;2), clusters building, factorial vectors and analysis of independent items. The results of the secondary dimensions (no show, seasonality and waiting time) have indicated that the subjects are engaged to avoid the no-show practice, trend to go to Establishments according to the present seasonality and are sensitive to waiting time. Pursuant to the main dimensions (scheduling and free on demand systems), it was detected different levels of acceptance, which may indicate in principle that the two systems are complementary and does not exclude each other. Therefore, it seems to be viable the adoption of a hybrid model in the referred operation, under which the offer of medical exams would occur through the use of the two systems so that customers could make their choice as preferred / Os serviços de medicina diagnóstica são perecíveis e a demanda é variável, características que dificultam a maximização dos resultados. Os prestadores tradicionalmente ofertam os exames por meio do sistema de agendamento de horário sem, no entanto, superar a ineficiência provocada pelo não comparecimento dos clientes (no show). O objetivo desse estudo foi investigar o nível de satisfação dos consumidores de medicina diagnóstica relativamente ao modelo operacional com agendamento, a aceitação para um novo modelo sem necessidade de agendar horário (demanda livre) e analisar três dimensões secundárias comuns aos dois modelos. A revisão da literatura contemplou a evolução histórica dos serviços diagnósticos no Brasil, bem como os processos, oportunidades e desafios associados a tal desenvolvimento. Verificou-se que a relação existente entre a perecibilidade e a sazonalidade compromete a rentabilidade das empresas, pois impede o melhor aproveitamento da capacidade instalada, a diluição das despesas e o retorno dos investimentos. A etapa referente à evolução do marketing de serviços e relacionamento evidenciou a importância de realizar a pesquisa com os próprios usuários do serviço. Trata-se de uma pesquisa de abordagem quantitativa com delineamento exploratório-descritivo, realizada com 2.545 clientes de uma empresa privada de medicina diagnóstica em 2013. A coleta de dados ocorreu por meio da aplicação de questionário e foram utilizadas as seguintes técnicas estatísticas para a apuração dos resultados: comparação de médias, relações entre variáveis categóricas (&#967;2), construção de Clusters, vetores fatoriais e análise de itens independentes. Os resultados das dimensões secundárias (no show, sazonalidade e tempo de espera) indicaram que os sujeitos estão engajados para evitar a prática do no show, tendem a frequentar os estabelecimentos conforme a sazonalidade atual e são sensíveis à espera. Quanto às dimensões principais (sistema com agendamento e sistema com demanda livre), foram evidenciados diferentes níveis de aceitação, o que indica, a princípio, que os dois sistemas são complementares e não excludentes. Assim, parece viável a adoção de um modelo híbrido de operação, no qual a oferta dos exames se daria pela utilização dos dois sistemas para que os clientes optem conforme a preferência

O modelo de fila M/M/n+G pode ser usado para descrever o comportamento de uma Central de Atendimento. Nesse modelo as chegadas são Poisson com taxa lambda, o atendimento é exponencialmente distribuído com taxa mi, há n atendentes e os tempos de paciência dos clientes têm distribuição geral. A espera do usuário em fila não pode ultrapassar um tempo (paciência) que tem distribuição G e, se isto ocorrer, ele abandona o sistema. Mandelbaum e Zeltyn [2004] mostraram que existe uma relação linear entre o tempo médio de permanência na fila e a probabilidade de abandono nesses modelos quando a paciência é exponencialmente distribuída. No presente trabalho, estudamos essa relação no caso de distribuiçãao de paciência do tipo mista (com partes discreta e contínua), em que buscamos representar a reação dos usuários às mensagens gravadas reproduzidas periodicamente para aqueles que estão esperando atendimento. Utilizamos duas distribuições de paciência: Exponencial Mista e Uniforme Mista e percebemos que não há uma relação linear entre o tempo médio de espera na fila e a probabilidade de abandono. Observamos que para uma mesma taxa de chegada, o tempo médio de espera na fila é menor para a distribuição de paciência mista quando comparada com a Exponencial ou Uniforme de mesmos parâmetros. Analisamos o que ocorre com essa relação quando alteramos a distribuição do atendimento e percebemos que ela é mais afetada pela média e pelo coeficiente de variação do que pela particular distribuição escolhida para o tempo de serviço. / The M/M/n+G queueing model can be used to describe the behavior of a Call Center. This model has Poisson arrivals with rate lambda, service times are exponentially distributed with rate mi, n agents and the client´s patience time has general distribution. The waiting in line could not exceed a time (patience) which has distribution G, and if it occurs, the client leaves the system. In this models, Mandelbaum and Zeltyn [2004] showed that there is a linear relationship between average waiting time in queue and the probability of abandonment if the distribution of patience is Exponencial. In this work, we study this relationship in the case of patience with mixed distribution (which has discret and continuous parts). Through mixed distributions we try to represent the user´s reaction to recorded messages reproduced periodically when they are waiting for service. We have used Mixed Exponencial and Mixed Uniform distributions and, in both of them, there is not a linear relationship between average waiting time in queue and the probability of abandonment. We observe that for the same arrival rate, the average waiting time in line for mixed distribution is smaller than Exponencial or Uniform distributions with the same parameters. Also, we study the effect on waiting time and abandonment of different distributions of service and we observe that it is more affected by the coeficient of variation and average that by the particular distribution chosen for service.