At its early stage a research and development program is a risky venture. Numerous alternative approaches have to be tested in order to determine a successful one if any. Clearly enthusiasm and even stubbornness will playa significant role, but economic considerations may also help to efficiently allocate the effort and in particular to specify a somewhat "reasonable" time-cost trade-off for the completion of the project. "Reasonable" can only be properly defined once the main features of the situation have been quantified and related to each other within a model. Then logical analysis of the model may be used to provide guidelines for action. 

The objective of this paper is to briefly review the analysis of a sampling process which appears to be used as a model in the research and development literature.