This paper will examine the use of quantitative and qualitative methods as complementary research methods. It asks the fundamental question whether these two approaches can be used jointly in a principled manner. The pressure in educational research has been towards using the two methods alongside each other. In applied research the use of the two approaches in the same project is accepted yet ...

Over approximately the last 20 years, the use of qualitative methods in educational research has evolved from being scoffed at to being viewed as useful for provisional exploration, to being accepted as a valuable alternative approach in its own right, to being embraced as capable of thoroughgoing integration with quantitative methods. Progress has been halting, and it is not surprising that ce...

In this paper, we consider a two-phase queueing system with impatient customers and multiple vacations. Customers arrive at the system according to a Poisson process. They receive the first essential service as well as a second optional service. Arriving customers may balk with a certain probability and may depart after joining the queue without getting service due to impatience. Lack of servic...

In this paper, we present an analysis for an M/Ek/1 queuing system with balking and state-dependent service. Customers are served with two different rates depending on the number of customers in the system. If a customer on arrival finds other customers in the system, it either decides to enter the queue or balks with a constant probability. We first formulate the queuing model as a quasi-birth...

We describe main models and results of a new branch of the queueing theory, theory of retrial queues, which is characterized by the following basic assumption: a customer who cannot get service (due to finite capacity of the system, balking, impatience, etc.) leaves the service area, but after some random delay returns to the system again. Emphasis is done on comparison with standard queues wit...

The paper deals with modelling a finite single-server queuing system with the server subject to disasters. Inter-arrival times and service times are assumed to follow the Erlang distribution defined by the shape parameter r or s and the scale parameter rλ or sμ respectively. We consider two modifications of the model − server failures are supposed to be operate-independent or operate-dependent....

A customer who places a tentative order at a steel mill customarily receives a due-date quotation, namely the date by which the mill says that it will ship the order. The steel mill wants the due date to be early enough so that the customer won’t balk (withdraw the order), but late enough so that the probability of tardiness is low. This note obtains expressions for the tardiness probability at...

Customer retention is the key issue in the organizations facing the problem of customer impatience. Firms are employing a number o f customer retention strategies to sustain their businesses. An impatient customer (due to reneging) may be convinced to stay in service system for his service by utilizing certain convincing mechanisms. Such customers are termed as retained customers. Queuing with ...