What you need to do

Provide sufficient detail to allow the market to respond, while allowing scope for innovation where appropriate. You should normally use an Output Based Specification (OBS) that focuses on what you want, not how a supplier is to provide it. This challenges suppliers and gives them the scope to develop innovative solutions. But note that in certain circumstances it may be essential for you to specify exactly what is required in detail e.g. for specialised laboratory equipment or to meet a specific environmental condition. For detailed guidance see the briefing on Specification Writing.

Include performance measures as part of the requirement - how to confirm quality, etc. Determine the ways in which the requirement might be implemented - one package of work, several phases etc.

For IT enabled business change projects:

• Phased implementation should be the norm - proposed use of 'big bang' implementations must be justified.
• Serious consideration should be given to the use of Commercial Off The Shelf software(COTSS) in preference to bespoke development.
  

Points to consider

For complex or novel requirements, developing the specification can be an iterative process, starting with a high level statement of the requirement that is progressively refined to arrive at the level of detail needed for the final specification.

As part of this process it can be beneficial to issue a draft or high-level specification to suppliers after the supplier selection stage to seek input to help develop the full specification.Such responses are intended to inform the requirement, not for evaluation purposes.

Care should be taken that responses do not influence the final specification in a way that favours a particular supplier or solution.