Simultaneity means that two or more things exist at the same time. For example, in many services the guest is present when the service is rendered, such as the preparation of a cocktail at a hotel poolside bar. Consequently, the customer‟s judgement about the service quality is influenced by each and every circumstance observed during the process and especially by the delivery of the cocktail by the waiter. Dotchin (1992) states that the participation of the guest in the service process is fundamentally different from material processing operations (MPO) and customer processing operations (CPO). The difference arises because of the extent to which, in the case of CPO, it is necessary to manage intangible elements within the production process itself. The waiter serving the cocktail must first determine the individual customer's expectations and then customise the service he provides on the basis of his diagnosis. The waiter also needs to assess the quality of his performance as it takes place, against the assessment of the guests expectations, while remaining ready to detect and respond to any adverse guest reactions which may occur.