Consumer Myths     

A customer who request computer software might be a person at the next desk a technical group down the hall the marketing or sales department or an outside organization that has requested software under contract. In various cases the customer believes myths about software because software responsible managers and practitioners do little to correct misinformation > Myths lead to false expectations (by the consumer) and ultimately dissatisfaction with the developer.

Myth: A general statement of target is sufficient to start writing programs we can fill int eh details later.

Reality:    poor up-front definition is the major cause of failed software efforts. A formal and detailed description of function information domain, validation criteria is essential, design constraints and performance interfaces. These characteristic can be determined only after by communication among customer had developer.

Myth Project needs continually change, but change can be simply accommodated because software is flexible.

Reality   It is true that software needs do change with the time but the impact of change varies with the time at which it is introduced. Figure 1.4 illustrates the impact of changes in software. If serious attention is given to up-front definition early requests for change can be accommodated simply. The customer can review needs and recommend modification with relatively little impact on the cost. When changes are requested during software design cost impact grows rapidly. A design framework has been established and Resources have been committed. Change can cause upheaval which needs additional resources and major design modification for example additional cost, Changes in function, other characteristics or performance interfaces during implementation the code and test have a severe impact on the cost. When Change requested after that software is production, use can be more than an order of magnitude more expensive than the similar change requested earlier.